816 ANATOMY OF VERTEBRATES. 



sent work serves as well as those given by Pouchet, to exemplify 

 it. The proligerous pellicle, due to the resolution into molecules 

 of the primarily formified bacteriums and vibrios of infusions, 

 answers to the molecular contents of the ovisac. In both instances 

 the molecules or granules aggregate into groups forming spheroids 

 more opake than the rest (as in fig. 555, A): as the aggregation 

 and coalescence advances the sphere becomes more opake, more 

 definite : then a clear line marks its inclusion within a membrane, 

 analogous to a f zona pellucida,' and proclaims its individualisation 

 (as in ib. B). Next appears a clear nucleus, answering to the 

 germinal vesicle (as in ib. c). Fission of the nucleus is followed 

 by that of the monad, which may thus multiply itself within the 

 primary envelope (Chlamydomonas, CCXLIX. fig. 29), like the 

 cleavage-formation of the germ-mass : ciliary organs are acquired 

 in both instances, rotating the germ-mass in the mammalian 

 ovum, and extricating the monad from its proligerous bed ; 

 whereupon it revolves or darts along, a free animalcule, in the 

 subjacent liquor of the infusion. 



In neither instance is there any support, from observation, of 

 the derivation of germ-mass or of monad by evolution out of a pre- 

 existing cell : in both instances have the processes of epigenesis 

 or building up ab initio been repeatedly seen and traced. 1 



In the case of the ciliate infusory the following are the primary 

 or preliminary steps in the formation of the proligerous pellicle, 

 or ' Burdach's mucous layer.' In the clear filtered infusion a 

 slightly opalescent appearance precedes the formation of the 

 thin superficial film. This consists of molecules of various sizes, 

 the most minute testing the highest powers of the microscope. 

 These molecules I attribute to the act of formifaction, which 

 in reference to organic matter in solution corresponds with the 

 crystalline aggregation of mineral matter in solution. Solution 

 of organic matter, such as clear serum from a blister, enclosed in 

 6 goldbeater's ' skin or other close membrane, and inserted be- 

 neath the integument of a living Mammal even distilled water 



o o 



which so placed obtains the elements of formifaction by endosmosis 

 show its results in the form of granules, white blood-cells, pus- 

 globules, &c. These experiments need repetition and modification 

 mainly in reference to the objection that such ( leucocytes ' might 

 have wriggled their way, like Abamce, from without, through the 



1 cccx". pp. 352-388. cccxi". pp. 133-253. cccxn". pp. 121-129. cccxm". p. 

 1046. cccxiv". p. 974. cccxv'. p. 467: Mantcgazza spent sixteen consecufive hours 

 in observing this genesis. 



