Organisms Consisting of One Cell 269 



tion of development (Entzmckhing) and embryology {Ent- 

 wicklungsgeschiclite) . "By development," they say, "we 

 understand the course of those form-changes through wliich 

 organic figure is produced." *'* And "embryology is a 

 descriptive presentation of the developmental processes of 

 the organism." ^^ But development of the protozoa is as 

 rigidly excluded from all the discussions in this newer general 

 part as it was from the older special part. 



"The science of embryology," we read, "has for its sub- 

 ject-matter the growth of animals from the time when they 

 first appear as germs in the bodies of their parents until 

 they reach the adult condition and are able to produce simi- 

 lar germs themselves." ^- Though this statement seems 

 broad enough to cover the development of many, at least, 

 of the protozoa, yet when one turns to the body of the work 

 to see how these animals have fared, he is quite taken aback 

 to find that they simply are not mentioned at all. So the 

 inference seems unescapable that according to the views of 

 the embryologists responsible for the above statement, in 

 this great section of the animal w^orld there are no such 

 things as germs contained in the bodies of parents, which 

 grow to reach the adult condition. According to their 

 viexcs, I say, because not for a moment is it to be supposed 

 they are unaware of the fact that one of the primary 

 subdivisions of the protozoa, the sporozoa, receive their 

 name from the almost universality among them of repro- 

 duction through sporulation, the spores or germs being 

 in most cases formed within the encysted parent animal. 

 And the authors are, of course, familiar with the conjuga- 

 tion of male and female gametes in many species to produce 

 the zygote, the parent of the spores, from which in turn the 

 adult animals are developed. 



Although it is unfortunately true that there is dearth 

 of observational knowledge on the growth of the adult from 

 the spores, yet the dozen and more developmental stages 



