and Laboratory Methods. 1691 



useful place in teaching botany and zoology, limited as their value has been. 

 One needs only to see upon the screen the magnified pictures of live plants and 

 animals exhibiting their motions, morphology, much of their anatomy, and even 

 physiological phenomena, with all the parts in normal colors, sizes, and relations, 

 to appreciate the value of the new projection methods which produce instructive, 

 interesting and valuable living charts. 



The apparatus, methods, and especially the little kinks in manipulation of 

 the apparatus and living organisms, on which much of the success in biological 

 projection depends, will be the subject matter of this series of articles. The 

 author makes no claims to have solved all the problems or that other workers in 

 this line have not invented methods which he will be pleased to adopt ; but he does 

 hope to assist many busy workers in the attainment of long wished for results 

 and to bring biological projection into the place which it alone can fill. 



To accomplish certain and definite results when using many species of active 

 animals, it is necessary to reduce or entirely check the voluntary activities of the 

 animal by the use of suitable anesthetics or hypnotics. While looking for a 

 hypnotic applicable to various animal types, the writer came across a new hyp- 

 notic used by the medical profession and called Chloretone by its manufactur- 

 -ers.* Beginning its use in the spring of 1900 and finding it of exceptional value, 

 ■exact experimental tests were made and formulae for its use worked out on typi- 

 cal animals ranging from amoebae to warm blooded vertebrates. The methods 

 were demonstrated to the members of the Biological Round Table (teachers of 

 biology in the Chicago high schools) and in the summer of 1901 were a part of 

 a course in the " Technique of Biological Projection and Hypnosis of Animals " in 

 the University of Chicago. The term anesthesia is now used instead of hypno- 

 -sis, the latter term carrying the idea to many people that mental processes, rather 

 than chemical agents, are used in inducing the passive state in animals used in 

 this work. As these methods of producing anesthesia very greatly increase 

 the number of species available for projection, they necessarily become a part of 

 the treatment of the subject. 



A general idea of the possibilities of biological projection may be gained 

 ^rom an enumeration of some of the common plants and animals which can be 

 xnade to exhibit not only their external forms and motions, if they are motil, or 

 like Spongilla and fresh-water clams produce currents in the water, but are, or 

 can be made, sufficiently transparent to permit of entire or partial optical sec- 

 tions being projected with sufficient magnification and illumination to make the 

 living chart visible to an entire class or an audience of several hundred people. 

 The types enumerated below are a part of those regularly used in class studies 

 -and public lectures. 



Beginning with the bacteria, it is possible to exhibit medium sized motil spe- 

 cies when using sunlight, and large species, e. g., Spirilhim vohitans, with electric 

 arc illuminant and ordinary microscope objectives. Yeasts, pleurococcus, dia- 

 toms and desmids present a wide range of simple types, many of them available 

 for high power work up to 10,000 diameters. Volvox makes a most interesting 

 picture, combining the various stages, sizes, graceful motions and details of struc- 



* Parke, Davis & Co., Detroit, Mich. 



