398 M. E. Claparede on the Theory of the 



as tliey possess oue contractile vesicle (at least Evglena viridis 

 does so)*. Many Volvocince also appear to possess contractile 

 vesicles. It is moreover an idle dispute to attempt to decide 

 whether these loAV organisms he animal or vegetable ; for even 

 if the question be decided, the two beings would still remain so 

 closely related, that it would be a mere splitting of hairs to place 

 one in one kingdom and the other in another. If there exists 

 an actual division in Nature, it is that between the organic and 

 inorganic kingdoms; and even there we must shut our eyes to 

 certain Polycystina, and especially to some of those agglome- 

 rations of organized raphides, as it were, raised to the state of 

 independent beings, to which the name of ThalassicoUce has been 

 given. That my meaning may not be misunderstood — it is with 

 the relation between animals and vegetables as with those of the 

 group of Fishes with the neighbouring groups. In its broad 

 features, the class of Fishes is one of the best existing in zoology ; 

 but if we descend into details, we shall find the limits, which at 

 first appeared so well marked, become less and less distinct. If 

 you ask a young student, he will very readily give you a definition 

 of a fish, by means of its biconcave vertebrae, its heart with two 

 cavities, its branchi;e, and some peculiarities of its brain. But if 

 you question an ichthyologist, he will be nmch morQ embarrassed ; 

 for he knows, on the one hand, that there are fishes with lungs 

 and a heart with three cavities {Sir en aides f) ; and, on the other, 

 that there is a fish without vertebrse, without a brain, and with- 

 out anything that can be called a heart [Amphioxus). 



I hope I shall be pardoned for this digression, the only object 

 of which was to show that it is not without reason that the 

 vegetables and animals have been united in treating of the 

 general phajnomena of fecundation. AVe have ascertained the 

 probable universality in the organized kingdom of the penetration 

 of the spermatozoids into the ovules ; but what is the part which 

 they play when once arrived there? According to MeissnerJ, 



* To those who attach importance to chemical and jjhysical characters 

 I would observe, that, according to Angstrom's observations, whilst the 

 green extract of the Phanerogamia gives three brilliant streaks in the 

 spectrum, that of Euglena viridis only gives two, one in the green, the 

 other in the red. It is remarkable that in this respect the Euglena behaves 

 exactly like the three Conferv^e in which Angstrom has studied the pro- 

 perties of chlorophyll {Conferva glomerata, a Zygnema, and a Vauclieria). 

 Poggendorff's Annalen, xciii. 



t It is to be observed, that the opinions of zoologists as to the true 

 position of these animals {Lepidosiren and its allies) are by no means 

 settled, so that M. Cla))arede is scarcely warranted in treating them as 

 members of the class of Fishes. — Transl. 



X Beobachtungen liber das Eindringen der Samenelemente in den 

 Dotter, No. i. Zeitschr. fiir wiss. Zoologie, vi., Sept. 1854. 



