116 



evidence of the occurrence of copulation in some species which he 

 has had under observation. His preliminary notes * on this 

 subject have, by the consent of the author, been summarized and 

 translated into French by M. Schlumberger in a paper published 

 in La Feuille des Jeunes Naturalistes, in May, 1896, to which I 

 am indebted for a knowledge of this part of M. Schaudinn's dis- 

 coveries. 



Prior to the discovery now referred to, copulation had been 

 observed to take place among some of the Rhizopoda, but no 

 exact determination had been made of the changes that were 

 thereby induced in the individuals concerned in the act ; and, 

 prior to the observations made by Schaudinn, no one had noted 

 the occurrence of copulation among the Foraminifera. The 

 researches of Maupas and Hartog on the methods of reproduction 

 among the lower forms of life, both in the vegetable and animal 

 kingdoms, published about five years ago, undoubtedly prepared 

 the way for the recent discoveries among the Foraminifera. 

 Maupas had pointed out that in the lower organisms long-con- 

 tinued propagation by fission without fusion resulted in a state 

 of senescene and ultimate extinction. This has been abundantly 

 confirmed by Professor Hartog, who says : — " We have evidence 

 on all sides to show that a sexual reproduction, colonial or 

 cellular, is rarely continued indefinitely in those organisms which 

 have a sexual process. After a certain continuance of asexual 

 reproduction the strain deteriorates." f What the author calls 

 a "rejuvenescence " must be attained by fusion of individuals to 

 prevent degeneration, and maintain the vigour of the organism. 

 To reach this rejuvenescence, in the case of the Protozoa, Hartog 

 notes that there are two leading types of reproduction, which he 

 designates respectively Karyogamy and Plastogamy. Karyogamy 

 (a term first used by Maupas) is defined by Hartog to be " the 

 fusion of two or more nuclei as well as of the cytoplasts into a 

 uninucleate cell." { " Plastogamy is the cytoplastic union of 

 cells without nuclear fusion. This, of course, brings about com- 

 plete mixture of the cytoplasts, comparable to that of the nuclei 

 in Karyogamy." § In the discoveries of Schaudinn, to be im- 

 mediately referred to, it will be seen that copulation among the 

 Foraminifera is plastogamic rather than karyogamic. 



For the purposes in view, Schaudinn has chiefly confined his 

 observations to two species of Foraminifera, Patellina corrugata 

 and Discorbina globularis, both of which are common forms in 



* F. Schaudinn, Ueber Plastogamie bei Foram. ; Sitz. Bericht. d. Oesellsch. 

 Naturforsch. Freunde, 1895, No. 10. 



t"Some Problems of Reproduction," by M. M. Hartog, Quar. Jour. 

 Micro. Soc, vol. XXXIII. (1892), p. 64. 



X Ibid. § Ibid. 



