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published data. Being an object of great interest from both the botanical and horticultural standpoint an immense amount of literature dealing with the Dodder could be obtained, but as the plant is a dangerous pest the whole of the practical information available dealt with methods for its destruction, and not a hint could be obtained as to how it might be induced to grow. As a last resource seed of the closely allied Dodder of the Flax, (Cuscuta epilinum) was tried. Within three days our pans presented the appearance of a miniature lawn, practically every seed having germinated, and the performance could be easily repeated at seasons of the year when flax plants were non-existent and when germination of the Dodder under such circumstances would be absolute suicide.
With the consideration of Kinephotomicrography we enter upon an altogether different aspect of nature recording. Instead of long exposures, low powered lights, and troubles arising chiefly from the extreme slowness with which our subjects perform their various functions we have short exposures, intense illumination and difficulties arising from the fact that by increasing amplification we correspondingly reduce the light upon the film, magnify movement, and conseguently exaggerate any trace of vibration. Added to this the intense light necessary for our purpose is often distasteful, injurious or even fatal to many of the organisms whose movements we desire to record.
A notion is very prevalent that in order to undertake work of this kind heavy electrical currents are indispensable. Nothing could be further from the truth. Admittedly an arc has many advantages, particularly in the matter of convenience, but one is so often faced with circumstances in which suitable current is unobtainable that details of methods by means of which good service may be coaxed out of the sun or a cylinder of oxygen may not be amiss. As a preliminary, therefore, I wish to confess that I employ no current beyond a six volt accumulator.
A few words concerning the fundamental principles of photomicrography may not be superfluous.
If, whilst using a compound microscope with a well-illuminated field of view we hold a ground glass screen a short distance above the eye-piece we find upon it a small image of the object under observation. By moving this screen further from the instrument and adjusting the focus we obtain an increasingly amplified picture. This image is of course capable of producing an impression on a plate, or film and a photomicrograph is obtained.
The initial magnification of the object is carried out by the objective, upon whose construction and characteristics the power of resolving details is dependent. The eyepiece further amplifies the image produced by the objective, but adds nothing to it. Any degree of further enlargement may be obtained by increasing the distance between the plate and the microscope, but nothing is gained by a mere exaggeration of dimensions. Low degrees