CELLS. -13 



one kind are formed, while the others live in it, is very 

 interesting. In the blood-globules there is a considerable 

 preponderance of solid constituents, since the blood-plasma 

 only contains about 10 per cent, of solids, which is evidence 1 

 that there are cells whose contents do not attain an equilibrium 

 with the cytoblastema by which they are supported. With 

 regard to particular substances, the blood-corpuscles contain 

 more fat ; hsematin, which is not found in the plasma ; more 

 potass and phosphoric acid; less chlorine, extractive matters, 

 soda, and earths. The yelk of the hen's egg contains also 

 considerably more solid constituents than the blood, which 

 however is here less surprising than in the blood-corpuscles 

 which swim in the blood-plasma. It is interesting, that the 

 relative proportions of the different substances are quite diffe- 

 rent in this case from the other. We have, namely, an exceed- 

 ingly large quantity of fat, more protein and salts; and among 

 the latter, again, more potass, and also more earthy salts. 



Even these facts indicate a considerable independence of 

 action in the cells; but those which have been lately made 

 known by Ludwig, tend still more forcibly in the same 

 direction ; for the influence of the nerves upon the salivary 

 glands discovered by this observer must, I believe, be so inter- 

 preted, that it is not only the membranes propria of the 

 vesicles of the salivary glands, which are so altered in 

 their molecular relations by the nervous influence that they 

 directly exercise an energetic attraction upon the blood-plasma 

 which surrounds them, but the epithelial cells which line 

 them also. If this really be the case, we have an insight into 

 an altogether new condition regulating the absorptive powers 

 of cells, and at the same time cell-life is brought into such 

 connection with the activity of the nervous system, that it no 

 longer appears out of reason to speak of the positive functions 

 of the latter. Such relations are in nowise opposed to analogy, 

 since in the contractile elements we have already a connection 

 between nervous activity and the modification of cell-contents, 

 which perhaps upon further investigation may come under the 

 same general category as the foregoing. In any caoC, these 

 considerations lead anew to an exact investigation of the 



1 [This would be true only if the major part of the solid constituents of the blood- 

 corpuscle were its contents; this, however, is not the case. — Eds.] 



