MEIOSIS 115 



branchiarum, Collin (1909) described a reduction of from six to three 

 (Fig. 495, 5 and 6), while Enriques (1908a) in Chilodon uncinatus saw 

 a reduction of four to two, and (1907) in Opercularia coarcta a reduction 

 of sixteen to eight (p. 1174), In all these cases the conjugating or gamete 

 nuclei possess half or the haploid number of chromosomes, while the nuclei 

 resulting from the union of the gamete nuclei have the full or diploid 

 number, which is maintained at all subsequent divisions. This is the 

 reverse of what occurs in the gregarines and coccidia, as described by 

 Dobell and Jameson, and Reichenow. 



In connection with the process of union of gametes many so-called 

 reduction or maturation processes have been described. In Eimeria 

 schubergi, Schaudinn (1900), for instance, described as a maturation pro- 

 cess the breaking up and extrusion from the nucleus of the macrogamete 

 of the large karyosome (Fig. 337, ii). From what has been said above of 

 the reduction division of the nuclei of coccidia, gregarines, and ciliates, it 

 seems highly improbable that such a process is a reduction at all. In 

 the case of Cyclosjpora caryohjtica, another coccidium, Schaudinn (1902) 

 described the macrogamete nucleus as dividing twice, one of the products 

 of each division degenerating (Fig. 341). This again is explained as a 

 maturation process for the macrogamete nucleus before it is fertilized by 

 the microgamete. A similar process is said to take place in the case of 

 the parasites of malaria. The macrogamete, before fertilization in the 

 mosquito's stomach, is supposed to extrude one or two polar bodies which 

 contain some of the chromatin of the nucleus (Fig. 391, i6). In the case 

 of the conjugation of the flagellate Copromonas subtilis described by Dobell 

 (19086), where two individuals fuse, before the union of the nuclei each 

 nucleus is said to divide twice to form two reduction bodies which de- 

 generate (Fig. 48). After this, the nuclei of the conjugating individuals 

 unite. From what has been discovered during the past few years regarding 

 the methods of reduction of the number of chromosomes in connection 

 with the union of gametes in the Protozoa, it is evident that many 

 of the processes previously interpreted as reduction or maturation 

 divisions of the nuclei need to be re-examined in the light of what 

 is now known. Till this has been done it is useless to speculate as to 

 their meaning. \ 



BLEPHAROPLASTS, PARABASALS, AND KINETOPLASTS. 



It has been explained above that amongst the Mastigophora the axis 

 of the flagellum is a filament (axoneme) which arises from a granule called 

 the blepharoplast. When there are two or more flagella, there arc a 

 corresponding number of axonemes and blepharoplasts. The several 



