478 BOTANICAL GAZETTE [JUNE 
two pert is hardly justifiable, where, as this plant shows, intergradations 
exist. 
JuEL,” studying R. Bischoffii, found that the cells of the median dorsal 
region of the thallus are arranged according to the so-called Euriccia pattern, 
while the wings have the Ricciella pattern; the smallest air chambers being 
bounded by 6 cells and the largest by 15. He attributes the presence of the 
4-sided air spaces of the middle region to the fact that the ventral cells grow a 
little more rapidly than do the dorsal cells. The increasingly larger air spaces 
of the wings are due to very unequal growth of the cells. This work is another 
example of how artificial and arbitrary distinctions frequently break down 
when the problem is attacked by an eobserver trained in morphological 
methods.—W. J. G. LAND 
Traumatotaxy and chemotaxy.—RITTER® has published an article on trau- 
matotaxy and chemotaxy of the nucleus. It adds little that is new and is not 
markedly critical. In the region of the wound the nuclei in the intact cells 
move toward the wound and enlarge somewhat. Light and gravity do not 
modify the reaction, while absence of oxygen and anaesthetics entirely stop 
it. After five or six days the nuclei recover their normal position; this agrees 
with the duration of the shageapmte od ss pebiematates sere s wounding. ie 
are a number of parallels between 
but the author concludes that the chemotactic effect of endosmosing solutes 
from the dead cells cannot account for any considerable part of the trauma- 
totactic response. The wound response is much more rapid than the response 
to chemicals; wounds also produce protoplasmic movements, while the chemi- 
cals do not. Rurrer believes that in the wound response the nuclei are pas- 
sively transported by the moving protoplasm; on this point his evidence is 
certainly not convincing. The effective chemotactic substances were salts, 
bases, organic acids, and carbohydrates. Inorganic acids and many organic 
substances were not effective-—WILLIAM CROCKER. 
Hybrids at Kew.—A list™ of all hybrids produced in the Royal Botanic 
Gardens at Kew, England, will surprise many by its shortness, considering 
the length of time during which Kew has been one of the great botanical 
clearing houses of the world, and the obvious advantages it has had on this 
account for the production of hybrids. The earliest hybrid produced at 
Kew was the result of a cross between Rhododendron Griffithianum and R. 
Hookeri, made in 1874; and in the 36 years from that time, until this list 
was published, 49 hybrids have been produced, and 12 failures are reported. 
* JUEL, O., Ueber den aaa Bau von Riccia Bischoffii Hub. Svensk. Bot. 
Tidsk. po ee pl. 7. figs. 5 
3 RITTER, Gaston, Ueber Hahah ae und Chemotaxis des Zellkernes. Zeit- 
schr. Bot. 3:1-42. 1911 
*4 Hybrids raised at Kew. Kew Bull. 1910:321-328. 
