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away with the exception of the grade containing Cyclops and anything else of approximately the same size. The gathering is now transferred, a little at a time, to small observation tanks, and my eagle-eyed assistant, Miss Bolte, with a pipette, removes all unwelcome intruders. The pure gathering is placed in a cylindrical vessel whose bottom consists of fine silk gauze and suspended, half submerged in running water. By this means all debris is carried away and they are in excellent condition whenever required. Thev may be fed, if necessarv, bv transferring the container to a culture of the minute organisms they favour. As the contents of the alimentary canal can easilv be examined one can judge their feelings in the matter of appetite.
For a slightly enlarged general view we place a tank containing a few dozen specimens under the microscope, using a low-power objective and no eyepiece. The ordinary spot-lens used for dark ground illumination fails to work under these conditions, so we employ an oblique beam of light upon each side of the object. As Cyclops appears very brilliant by this method of illumination oxy-coal gas will be found sufficient. Focussing is carried out by the reflex method.
Next we attempt a more highly magnified view of the creature swimming freely. This phase is by no means easy. Some method of observation upon the actual film is now essential and, even then, the manipulation of the mechanical stage is difficult, Cyclops being a creature which swims in a very jerky and erratic manner, and it will be remembered that if we are magnifying the object a dozen diameters we are amplifying the movement to the same extent. .Having completed this phase — or given up in despair — we next proceed to observe details of structure. The activities of the creature may now be restrained by some form of compressor and with care the breathing mechanism, the single eye, internal organs, egg-sacs and other parts can be demonstrated without injury to the subject. For this the reflex method of focussing may be employed. Finally, should we require details of the lifehistory of the creature the hatching young are segregated from the parents by means of sieves, and fed upon suitable organic cultures.
Microscopic objects which require speed-magnification to make evident their movements and development constitute a very extensive group, a considerable proportion of which appertains to the Flowerless Plants. The spores from which these plants normally spring are very minute objects, and unlike the seeds of the higher plants contain little reserve food substance. For the observation of their early stages of growth the only practical method seems to be that generally employed in laboratories, utilising films of agaragar or gelatine containing the food substances they require. In ordinary laboratory methods the cultures are fairly easily maintained in good condition for considerable periods, but the taking of frequent photomicrographs soon upsets the delicately balanced conditions of the « moist cell » and before long