121 
of pith follows incidentally, and in the following manner; in the 
absence of special organs, as nerves, to conduct the stimulus of an 
irritant, in vegetables irritation can only be conveyed from- cell to 
cell, and hence the further a cell is located from the origin of the 
irritation the less its effect will be felt. Now irritation within nat- 
ural limits can only serve to increase cell activity and growth. 
This is just what Darwin found in the cases which I have quoted; 
and it is just what I should expect to find in the plant under con- 
sideration. 
In the same manner it would seem reasonable to account for the 
great difference in size existing between the supported and the unsup- 
ported plant. This difference has long been noted, and doubtless 
Linnzeus and others following him founded their different species 
mainly upon that character. In the one instance the plant has, so to 
speak, every energy brought into full activity, while in the other, one 
great incitement to full activity is witheld. The former attains its 
full stature, the latter remains a dwarf. 
Laurence Jounson, M.D. 
319, West 26th St. 
§ 127. Fresh Water Algae.—Collected during the past three 
years, mostly within a circuit of about twenty miles around Beth- 
lehem, Penn., by Francis WOLLE. 
[Thirty species helieved to be new to the United States and ten entirely new discoveries 
are indicated by Italics. ] 
DESMIDIEA. 
1. Palmogloea, Ktz.— P. clamydospera, de By. 
2. Penium, Breb.—P. digitis, Breb.—P. Closteroides, Ralfs.—P. 
interruptum, Breb.—P. oblongum, de By. 
3, Closterium, Nitzsch.— C. obtuswm, Breb.—C. angustatum, Ktz. 
—C, striolatum, Ehrb.—C. lunula, Ehrb.—C. Ehrenbergii, 
Menegh.—C. Leibleinii, Ktz.—C. Dianae, Ehrb.—C. Venus, Ktz. 
—C, parvulum, Naeg.—C. Jenneri, Ralfs.—C. rostratum, Ehrb. 
—C. setaceum, Ehrb.—C. moniliferum, ak Ga lineatum, 
Ehrb,—C. acerosum, Ehrb.—C. turgidum, Ehrb. 
4, Tetmemorus, Ralfs.—T. Brebissonii, Menegh.—T. levis, Ktz. 
5. Pleurotaenium, Naeg.—P. Trabecula, Naeg.—P. clavatum, Ktz. 
—P. crenulatum, Ehrb.—P. hirsutum, Bailey.—P. nodosum, 
Bailey. 
6. Spirotaenia, Breb.—S. condensata, Breb. 
7. Sphaerozosma, Corda.—S. excavatum, Ralfs. 
8. Hyalotheca, Ehrb.—H. dissiliens, Breb.—H. mucosa, Ehrb, 
9. Bambusina, Ktz.—B. Brebissonii, Ktz. 
10. Didymoprium, Ktz.—D. Grevillii, Ktz. 4 : 
11. Desmidium, Ag.—D. Swartzii, Ag.—D. Swartzii, var. Ralfsii,— 
D. aptogonum, Breb. : : é 
12. Aptogonum, Ralfs.—A. Baileyi, Ralfs, finely in fruit. 
13. Cosmarium, Corda.—C. margaritiferam, Menegh.—C. Botrytis, 
Menegh.—C. ovale, Ralfs.—C. tetrophthalmum, Ktz.—C. con- 
spersum, Ralfs.—C. Portianum, Archer.— C. Ralfsii, Breb.— 
C. leve, Rab.—C. Cucumis, Corda.—C. pyramidatum, Breb,— 
