No. 603] ECOLOGY OF THE PROTOZOA 



161 



Trichodina pediculiis (on Hydra Volvox globator 



Blepharisma lateritia (Fig. 1) is usually described as 

 showing pink or even reddish hues, and occurring rarely 

 colorless. My experience has been to find the greater num- 

 ber of individuals colorless and a very few showing even 

 a faint trace of pink. In reproducing the colors of Pro- 

 tozoa in plates there seems to be a tendency to represent 

 them more vividly than they occur in nature. It is inter- 

 esting to place a small chart of spectrum colors on the 

 table near the base of the microscope and compare them 

 with the hues of those species of Protozoa usually repre- 

 sented as brightly colored. It has been my experience to 

 find that the (depicted) decided colors of some of the Pro- 

 tozoa show themselves to be only the faintest tints. 



Synura uvella (Fig. 2) is not entirely colonial in its 

 habit. I have found it sometimes singly, and often in 

 pairs. The normal number of individuals in a colony is 

 from 10 to 20. As many as 35 in one group have been re- 

 corded. The flagella are invisible unless iodine or some 

 good stain has been used. 



The Coleps sp. (Fig. 3) which I found so frequently in 

 this one group of samples I have never found since. It 

 was appreciably smaller than Coleps hirtus (Fig. 4), being 

 about 30 microns in length, whereas hirtus is 50. Eirtus 

 IS a species exhibiting a notable constancy in dimensions, 

 and this I found true also of all the numerous individuals 

 of Coleps sp. which I measured. Xo transitions in size 

 from one to the other could be found. Coleps sp. was not 

 the result of fission on the part of hirtus, for in all the 

 material my search revealed not a single individual un- 

 dergoing division. In api)earance and activities the one 

 form was the exact counterpart of the other, with a soli- 

 tary exception: the movements of Coleps sp. were at all 

 times much more rapid than those of hirtus. 



Lacrymaria olor (Fig. 5) described as a very variable 

 species, is variable in size almost entirely. Its form is 

 quite constant, and offers a virtually certain criterion for 

 identification. 



