148 CONJUGATION, MATURATION, AND FERTILIZATION 



therefore, whether the process is endogamous or exogamous, and the 

 same obscurity obtains in the union of free flagellated or ciliated 

 gametes. In some cases, on the other hand, there is no doubt about 

 the union of nearly related cells. Schaudinn ('94) described the 

 union of gametes of the same brood in Hyalopiis dujardinii, and it is 

 proved in the case of Basidiobolus lacertce by Loewenthal ('03); in 

 Actinospherium eichhornii by Hertwig ('98); in yeasts by Guillier- 

 mond ('02), and in cultures of free-living infusoria (Paramecium 

 aurelia) by Calkins ('02). 



Fig. 62 



C'^ 













D 



Endogamy in Plasmodiophora brassicffi. (After Prowazek.) A, portion of Plasmodium 

 showing ordinary vegetative nuclei; B, reconstruction of the gametic nuclei; C, division of 

 same; D, union of gametes formed about gametic nuclei; E. F, stages in fusion of nuclei and 

 formation of the spore. 



In basidiobolus, an intestinal fungoid parasite of the turtle, the 

 organism forms straight or branched hyphse composed of sister cells 

 lying end to end, and at maturity two adjacent sister cells conjugate, 

 a process recalling conjugation among the lower plants (conjugatse, 

 diatoms, etc.). In actinospherium the phenomena of fertilization are 

 much more complex and have been made the subject of careful study 

 by Hertwig ('98). The first evidence of the process is the encystment 

 of the adult organism and excretion of waste matters contained in the 

 protoplasm. The many nuclei of the ordinary forms are here reduced 

 to about 5 per cent, of the total by a process of fusion and absorption 

 in the protoplasm, and after this has occiuTed the mother animal 

 fragments into as many daughter cysts (cytospores No. 1) as there are 



