THE PLANT WORLD 311 



that the curling of Rhododendron leaves at low temperatures has been 

 shown to have any protective result or otherwise useful to the plant. So 

 far as we can see, it is merely the physical result of a physical cause — a 

 phenomenon which, by the way, occurs in other plants. The word 

 " metamorphosis," also, may not be applied to the simple curling of a 

 leaf — this is a mere matter of definition. That the curling of a leaf at a 

 temperature low enough to freeze it reduces the transpiration beyond 

 that which takes place, say, at freezing point, is also a gratuitous assump- 

 tion, and is therefore a matter subject to proof or disproof — and it would 

 appear probable that no effect at all would be found. 



The writer goes on to call this behavior the result of irritability and 

 regards it as " somewhat ( ! ) analogous ' ' to the movements of clover 

 leaves and tulip petals under far different conditions. This comparison 

 can scarcely be justified. The one in question is probably a purely 

 physical manifestation, quite unrelated to the response of protoplasm to 

 a stimulus. In one of the examples used for comparison, namely, the 

 clover leaf, certain changes in the environment call forth specific reactions 

 in the protoplasm, of which the leaf movement is the result. Thus, 

 though the temperature be kept constant, if sufiiciently high, changes in 

 the amount of light will call forth the response. Freeze a clover leaf and 

 the result would be quite absent. The analogy therefore is less instruc- 

 tive than misleading, and it would seem better to avoid its use. As to 

 the tulip petal, the frozen condition likewise does not enter into the 

 problem. 



How much harm may be done by such irresponsibility on the part of a 

 writer may be very hard to say. If we grant that it does none, may we 

 not justly say that it does no good. The serious aim of every writer on 

 scientific subjects, no matter if the treatment is intended to be popular, 

 should be to instruct while he pleases. There have been notable examples 

 of men who have done this, enough that we may gain assurance from 

 them that popular scientific writing, without making a contradiction in 

 terms, is still possible. To this end alone we offer this frank criticism. 



DEVELOPMENT OF THE EGG IN VAUCHERIA. 



Vaucheria has made for itself a lasting place as an important type for 

 study in the laboratory. Any new knowledge on such much-used and 

 well-known plants is the more welcome. We are glad, therefore, to point 

 out that new light has been thrown on the process of the egg-develop- 

 ment in this plant by B. M. Davis, of the University of Chicago.* 



Vaucheria is a filamentous alga, the nuclei of which are free in a 

 continuous protoplasm, internal cell-walls occurr ing only when swarm- 



*" Oogenesis in Vaucheria," Bol. GazeUe, 38: 81-98; August, 1904. 



