220 Dr Barry 07i Fissiparous Generation, 



specific peculiarities of the organisms. It is in perfect keep- 

 ing, too, with the known fact, that the kind of animalcule in 

 an infusion very much depends on the kind of organic matter 

 decomposing in it. 



76. Farther, the divisions and subdivisions of that remark- 

 able substance, the hyaline, to which I have so constantly re- 

 ferred, effected as they are by a process of assimilation, in- 

 cline me to believe, that even the minutest germ of the mi- 

 nutest disc and cell is derived from a previously existing germ. 

 The mysterious reappearance of parental qualities in offspring, 

 we probably shall never fully understand ; but certainly the 

 mystery is not lessened by the idea of "spontaneous generation." 



London, 26. 1 mo. {January) 1843. 



Explanation of the Plate. — Plate V. 



Fig. 1. Rabbit {Lepus Cuniculusj Linn.) Outline of an ovum of 24 

 hours from the middle of the Fallopian tube. Spermatozoa 

 are seen in its interior. This was the case with several 

 other ova of this rabbit. One contained more than twenty 

 spermatozoa. /," Zona pellucida." 6 s, The germ. (Par. 23, 

 note.) 



Fig. 2. Muscle from the heart (ventricle) of a frog (see pars. 48-51.), 

 Drawn as magnified 600 diameters. 



Fig. 3. Scheme shewing the situation of the nuclei in the muscular 

 fibril (se*^ pars. 48-51.) 



Fig. 4. Chlamidomonas Pulvisculus. — Stages of self-division. This 

 figure is from Professor Ehrenberg, who considers the pel- 

 lucid part in the centre to be the " spermatic gland.'' (Par. 

 56.) 



Fig. 5. Monas vivipara. « Is undergoing self-division. This figure 

 is from Ehrenberg, who remarks respecting « : '* In its in- 

 terior is to be recognised the incipient division of the cen- 

 tral spermatic gland, and three swallowed specimens of 

 Chlamidomonas pulvisculus; two of which remain in one 

 half, and one in the other." (Par. 58.) 



Fig. 6. Pandorina Morum. From Ehrenberg, who remarks, that the 

 contained animalcules " appear crowned." (Par. QQ.) 



Fig. 7. Monas bicolor. From Ehrenberg : '^ Perhaps only a state in 

 the development of Chlamidomonas." (Par. 5Q.) 



Fig. 8. Folvox Globator. From Ehrenberg. " First stages in the de- 

 i velopment of a young Volvox ;" « being the earliest, and 

 t the most advanced. (Pars. 53-55.) 



lopian tube without impregnation, I saw a body having a form somewhat the 

 same. This body, I think, may have had its origin in the macula germinativa of 

 the ovum. 



