7° 



CORRESPONDENCE. 



The Function of Stomata. 



The writer of the article entitled " Verworn's General Physiology," in the June 

 number of Natural Science, is surely ignorant of the recent work on the gaseous 

 exchange of foliage leaves, when he terms Verworn's statement, " that plants absorb 

 their gaseous food through the stomata," a curious slip. 



Stahl {Chew. Ceniralbl., 1894) has shown that when the stomata of a leaf exposed 

 to normal assimilative conditions are blocked, no formation of starch takes place ; 

 and more recently, Blackman {Proc. Roy. Soc, 1895) has definitely settled the question 

 for carbon dioxide by the employment of an elaborate and delicate apparatus for the 

 estimation of this gas, and has come to the conclusion that, under ordinary circum- 

 stances, the sole pathway in and out of the leaf is by means of the stomata. 

 Although the passage of oxygen has not been worked out, yet, as this gas diffuses 

 more quickly through fine openings than carbon dioxide, it is natural to suppose 

 that its chief entrance and exit is also through the stomata. Thus the whole gaseous 

 interchange of the leaf and the atmosphere appears on a more rational basis than 

 that on the old view of the passage through the cuticle, upheld until lately by some 

 botanists, but now untenable. 



Trinity College, Cambridge. , J. Parkin. 



[We are obliged for Mr. Parkin's correction. Our contributor must have over- 

 looked a note published in Natural Science (vol. vi., p. 228, April, 1895), i^ which 

 the result of Mr. Blackman's observations was given. — Ed. Nat. Sci.] 



The Retort of the Systematist. 



One would have thought that the time was long since past when a journal of 

 the standing of Natural Science would publish, under editorial sanction, such 

 sneers at the systematic naturalist as are contained in the review of Professor Miall's 

 work, in the April number. "The systematist, like the bibliographer, is necessary, 

 and there are faculties that may be trained by the pursuit of either industry." " Of 

 course. Professor Miall, like every other scientific man, knows the retort that the 

 systematist will make." It appears to be the reviewer's opinion, as perhaps also 

 Professor Miall's, that the "systematist" is only a sort of necessary evil, and not a 

 "scientific man." It was the fashion a dozen or more years ago for the morpho- 

 logist, and especially the microscopic morphologist, to express such opinions as does 

 your reviewer, and point, by way of contrast, to the real scientific work that he 

 himself did; he even yet appears to have a lingering contempt for the "systematist." 

 But these morphologists are now in danger of falling into the same contempt from the 

 real naturalist — " those who turn their back on the broad field of nature to peer 

 through a microscope at an infinitesimal portion of it." These are not the exact 

 words of Dr. Merriam, but they express his idea as well as that of most real 

 naturalists. The actual fact at the present time is that the "systematist" represents 

 the highest type of the naturalist, and no one can be a good naturalist who is not 

 more or less of a systematist. If natural history means the habits of plants and 

 animals only, or their physiology, then perhaps the systematist is not much of a 

 naturalist. If it means structure and relationships as well, then he is in a high 

 sense a naturalist. Pray let us hear no more of the cry that a systematist is a 

 necessary evil. He who gives utterance to such views only betrays his own 



