/^ 



lIFl 



Jd tft • ^^^ 



V "Notice tL' 

 f'^ Of I '^'^ i 



APPENDIX D. 



XCl 



' ^0 4e origin 

 obsen-ed in 



I 



'^'^m had 



underwent a kicj 

 « eight) smal ki. 



ie. 



J 



1. 



; 



The 



s 



bae may be rept 

 •tituent sabstance, 

 ]ie greater 

 nto Amceba?, aBd fc 



characters by the major part of the microscopists who have 

 observed them. Nevertheless, these forms, as well as the 

 particular size, which is often dependent upon accidental 

 circumstances, have no specific value. We shall see farther 

 on, that if a division into species can be established, it could 

 only have for its basis the mode of development, though 

 even this is found to be subjected to so many variations^ 

 attributable to the modifications of the medium in which the 

 animals are found, that it would be more natural to admit 

 only a single species, and to consider as simple varieties 

 the slight diff'erences which result from their mode of de- 

 velopment/ 



According to Lieberkiihn^ a relationship exists between 

 Amcebce and GregarincB which was previously unsuspected, 



kind to the relationship described by 

 Carter between such organisms and Astasm. He says^ he 

 has seen the conversion of pseudo-NavtcellcE, that have been 

 undoubtedly derived from GregarmcEy into AmcebcB, and he 

 states that he has also met with every transition between 

 such A?nce5cE and perfect Gregarincs, The transition com- 

 mences by the case or cvst-like wall of each -bseudo-Navicella 



though similar in 



to 



favourable 

 suit of a 



of their inediiiin,^M rupturing and giving exit to the soft contained matter, which 



at first much resembles a minute Amceha^ but gradually 

 assumes, by progressive growth and the formation of an 



■ t 



investing membrane around it, the characters of a Gregarina. 

 There has been much dispute as to whether the Gregari- 



res 



;on 



s of tbeir 



re pro 



duce itse 

 imitiw f«* 



lonad (pn 

 its life circk' 

 of ^^. 



nida are to be considered 



as independent organisms, or 



?nt 



hitherto 



descH' 



e 



^\rBcet^^ 



ass 



iiiii^- 



i 



been 



us 



eJas 



V 



merely as embryonic phases of other beings. Kolliker and 

 Leydig2 have advocated the notion that they are metamor- 

 phic stages of certain nematoid worms. But even then there 

 IS a further dispute as to whether the Gregarina becomes 



^^ 'Mem. de I'Acad. Roy. de Belgique/ 1854, t.xxvi. 

 In 'Journ. of Microsc. Science/ vol. i. p. 208, some of Leydig*s 



arguments are given. 



i 



l^- 



\ 



