IN THE VEGETABLE KINGDOM. 27 



8. Conjugation between the contents of opposite ends 

 of the same cell* Meloseira. 



The conjugate-spore has been seen, in the case of Spi- 

 rogyra, to split its coat in germination in two halves, and 

 emit a fusiform cell, from which others are budded off, so 

 as to form a confervoid filament like that in which the 

 spores were originally formed. -j- But the development is 

 not always so direct. Recent observations indicate that in 

 various Desmidiese the contents of the conjugate-spore are 

 transformed by repeated binary sub-division into numerous 

 derivative cells, which finally assume the form of the origi- 

 nal cells concerned in the act of conjugation, and are set 

 free by the dissolution of the outer wall of the spore. The 

 existence of such a process was rendered probable by the 

 observations of Focke, Jenner, and Ralfs on Closterium, and 

 has since been satisfactorily followed out in Cosmarium by 

 Horfmeister.J A similar multiplication of the spore-contents 

 has been noticed in one of the Palmellese (Palmoglea), and 

 in Thwaitesia and Mesocarpus among the Conjugate. 



There are other cases again in which the primary product 

 of the spore appears to be a cluster of zoospores, probably 

 reproducing the original form by a second process of germi- 

 nation. This is asserted by Pringsheim of Chlamydococcus 



* This subject is treated at some length by Braun (Rejuvenescence, 

 &c. Ray. Soc. Transl., pp. 284, et seq.) 



f This is the account given by Vaucher, Meyen, Smith, and Prings- 

 heim. Agardh, however, maintains that its contents become resolved 

 into Zoospores. The probability of an actual diversity in this respect is 

 confirmed by the observations of Pringsheim and Henfrey, that zoospores 

 are sometimes formed, instead of one large resting spore, as the primary 

 result of conjugation. See Ann. Nat. Hist., 2d Ser. XI., 210-297. 



Ralfs British Desrnidese, p. 11 and PI. XXVII. Annals of Natural 

 Hist., 3d Ser., I. 16. 



Micrographic Dictionary. See also Berkeley's Introduction to Cryp* 

 togamic Botany, p. 152, and Prof. Braun's Rejuvenescence in Nature. 

 Ray. Soc. Tranel., p. 136. 



c 2 



