Ill LIFE. HISTORY 43 



the zygote. Binary fission, on the other hand, is an example 

 of asexual reproduction. 



Notice also another important fact. The spores when 

 first emitted from the ruptured zygote are mere granules of 

 protoplasm, approaching as nearly as anything in nature to 

 the mathematical definition of a point, "without parts and 

 without magnitude." And, during its growth, a spore in- 

 creases not only in size but also in complexity, in other 

 words undergoes a progressive differentiation or development. 

 This is an instance of the principle known as Von Baer's 

 law, according to which "development is a progress from 

 the simple to the complex, from the general to the special, 

 from the homogeneous to the heterogeneous." In Heteromita, 

 then, we have our first instance of development, since in 

 simple fission there is no development, each product of 

 division being, from the first, similar to the parent in all but 

 size. 



Lastly, Heteromita is the first instance we have had of 

 an organism with a definite life-history. It multiplies 

 asexually by simple fission, producing free-swimming and 

 anchored forms : these conjugate in pairs forming a zygote, 

 in which, by multiple fission, numerous spores are formed : 

 the spores develop into the adult form, asexual multiplica- 

 tion begins once more, and so the cycle of existence is 

 completed. 



It must be borne in mind that further researches may 

 reveal the occurrence of a true sexual process in Amoeba 

 and Haematococcus pluvialis : in other species of Haemato- 

 coccus conjugation of the microzooids is known to take 

 place. 



monad which seeks and attaches itself to the anchored form as a male, 

 and the passive anchored form as a female gamete (see Lesson XII. ). 



