110 



KNOWLEDGE. 



March, 1913. 



When I had worked out the life-history of the and immediately adhere, the contents coalescing 

 organism thus far, I naturally imagined that I had very rapidly, and give rise to a swelling between 



Figure 103. 

 Polytoma granulosa sp. nov. 

 Normal free swimming form. 



Figure 104. 

 Stages in division. 



Figure 105. 

 Last stage in division and 

 form prior to conjugation. 



Figure 106. 

 Conjugation. 



settled the whole life-cycle, and it was only by the remains of the two envelopes. Finally, a round sac 

 chance that I found that there was more to learn, is formed, with rather thick walls, and finely granu- 

 These researches had been carried to this point in lar contents, with what is apparently a small bubble 



Figure 107. Figure 108. 



Stages in formation of winter resting spores. 



the summer of 1911, but being desirous of ascertain- 

 ing conclusively whether the products of conjugation 

 were ever more than two, I again made a series of 



Figure 109. 



Sac formed from 



conjugation. 



Figure 110. 



Natural division in winter 



spore. 



in the centre (see Figures 111 and 113). Practically 

 every monad in the late autumn forms these sacs, 

 reproduction by fission not taking place. In the 



Figure 111. 



Winter 

 resting spores. 



Figure 112. 



Induced division in spores 



by Suprarenal Extract and 



Atropine. 



Figure 113. 



Controls and spores showing 



division. (Suprarenal gland 



and Cadaverine). 



Figure 114. 



Free forms from induced 



divisions. 



All the figures are magnified 1000 diameters, except 111 which is enlarged 500 diameters. 



observations in October, 1911. I then was fortunate 

 enough to discover that there was a third method by 

 which a winter resting spore was formed. Two 

 organisms, both having their posterior ends com- 

 paratively free from granules, come into contact, 



course of some weeks the bubble-like body is absorbed, 

 leaving the finely granular contents surrounded by 

 the thick-walled sac. To study these spores further, 

 they must be kept continually moist on a live 

 slide of some sort through the winter, when it 



