of Edinburgh, Session 1883 - 84 . 
281 
hypothesis thrown out many years ago by M. Frdmy, our leading 
authority upon the chemistry of cellulose — that chitin and other 
analogous bodies really consist of cellulose linked with a proteid, 
seems well worth reviving. On this point the researches of Kruken- 
berg,* especially are promising light, f 
1 1 . Origin of the process of Sexual Reproduction . — The plasmodial 
stage which terminates the cycle, seems in the first place little more 
than a mere mechanical union of cells exhausted by prolonged 
activity ; in all normal cases it is soon followed by prolonged repose 
in the encysted state, and in the experiment upon invertebrate cor- 
puscles, by quiescence and death. In the plasmodia of Protomyxa, 
Myxomycetes, and of invertebrate corpuscles alike, notably Echinus, 
the union is followed by a brief but extraordinary intensification of 
amoeboid activity J — the cause of which, as passing from cellular to 
protoplasmic physiology, must be discussed in a subsequent paper. 
Some years ago considerable weight was attached by Sachs § to 
the hypothesis that the plasmodium formation of Myxomycetes might 
be regarded as a process of multiple conjugation. This view he now, 
however, withdraws, |j mainly on the ground that the nuclei have 
been shown not to coalesce as in true conjugation. It appears to 
me, however, that on the present theory the revival of that hypo- 
thesis, though in a somewhat different form, is inevitable. 
hfo one doubts that the sexual elements of plants and animals are 
represented by the very slightly differentiated conjugating cells 
of Spirogyra, or the almost undifferentiated cells of Mesocarpus. 
With these the conjugation of two Amoebse, two Actinosphseria or 
two Gregarines, are classified as a matter of course. But the recent 
observations of Gabriel upon the multiple conjugation of Actino- 
sphseria, or of Gruber upon that of Gregarines, leave no doubt that 
in these cases at least conjugation may be multiple. The only 
difficulty is that offered by the non-coalescence of the nuclei. But 
even if there were any certain grounds for supposing that the 
essence of the process lies in the union of the nuclei, rather than in 
* Krukenberg, Vergleich. Physiol. Studien, Bd. ii. 
t Ann. Sci. Nat. Bot., 1877. 
X See figure of plasmodium of Echinus in author’s papers in Arch. Zool 
Exp. VIII.; Proc. Roy. Soc. Bond., 1880, or Trans. Roy. Phys. Roc. Edin., 1SS2. 
§ Manual of Botany, 1st Eng. ed. 
11 lUd., 2nd ed., Appendix. 
