1895,] Vegetable Physiology. 1103 
neither the heat rays nor the less refrangible light rays cause closure. 
The above experiments then indicate that by the paraheliotropic 
movement leaflets are protected from the intense action of the blue- 
violet rays, and for this end all the leaflets on any one leaf need not 
` move through the same angle.” “ These observations emphasize the view 
already expressed by several investigators that orange, yellow, and 
green screens to the protoplasm, whether in the form of pigmented 
walls, of pigmented cell sap, or of chlorophyll are of a protective char. 
acter, and permit the normal functions to be carried on unimpeded by 
the action of the more intense blue-violet rays. But while such pig- 
ments are specially effective, the writer would suggest a similar func- 
tion for the thick, highly cuticularized epidermis that covers so many 
desertic plants, or plants that grow in places exposed to intense sun» 
light. One can easily prove by experiment that on a hot day a thin 
sheet of white paper considerably reduces the light intensity. A piece 
of Opuntia epidermis similarly obstructs the light rays, and even 
though the heat rays pass, we have seen that up to 40-43° C. no inju- 
rious effect follows to many plants. It might further be pointed out, 
as Wiesner has already done, that the hair covering on the leaves of 
certain plants will contribute to the same end.” The location of the 
movement in the pulvinus was determined by shading this organ from 
the direct action of the sun by narrow strips cut from an oak leaf. 
When the pulvini were thus shaded, leaflets that were inflexed 45 to 
50° re-expanded in a few minutes so as to form an angle of only 5 to 
10°. The time required to effect this change of position was only 13 
minutes in Cassia nictitans and 2} to 2% minutes in C. chameecrista, 
depending on the age of the leaf. Strips of mica of like —_— 
caused no movement.”—Erwin F. SMITH. 
Chalazogamy in Juglans regia.—Some years ago in Cina 
rina a peculiar genus of Australian and East Indian trees, dicecious, 
bearing aments, having the foliage reduced to scales, and superficially 
resembling Equisetacee, Dr. Treub discovered that the pollen tube 
does not enter the ovule by way of the micropyle but finally reaches 
the egg-cell by growing through the chalaza. This peculiar and alto- 
gether anomalous method of fertilization led him to found a distinct 
group of Angiosperms, sub-division Chalazogamia equal in rank with 
subdivision Porogamia, including the rest of the Digotyledons and 
Monocotyledons. Subsequently, Dr. Nawaschin, of Kiew, Russia, dis- 
covered that the same thing occurs in the Betulaceæ, and now in Ein 
neues Beispeil der Chalazogamie (Botanisches Centralblatt, Bd. 63; 
1895, pp. 353-357) the same author states that he has found chala- 
