118 



THE AMERICAN MONTHLY 



[June, 



eight or ten years ago, Mr. Royston-Pig- 

 got described an apparatus which was 

 nothing more than an iris-diaphragm, 

 made by the Messrs. Beck, placed above 

 the objective. 



— In The Northern Microscopist Mr. 

 J. B. Dancer has suggested a very simple 

 plan of limiting the angular aperture of 

 objectives by means of diaphragms. He 

 cuts a shallow recess in the upper part of 

 one of the female screw parts of a double 

 nose-piece, into which the different dia- 

 phragms can be successively dropped, and 

 lifted out with a wire hook. 



— Dr. H. D. Schmidt, of New Orleans, in 

 an article on the prevention of yellow 

 fever, made the following declaration re- 

 garding aerial disinfection : " Aerial disin- 

 fection, as commonly practiced in the 

 sick-room, is either useless or positively 

 objectionable, owing to the false sense of 

 security it is calculated to produce. To 

 make the air of a room smell strongly of 

 carbolic acid by scattering carbolic pow- 

 der about the floor, or of chlorine, by 

 placing a tray of chloride of lime in a cor- 

 ner is, so far as the destruction of the 

 specific contagia is concerned, an utterly 

 futile proceeding." 



When we consider the power of the 

 minute, so-called germs of disease to resist 

 destruction by chemicals added to solu- 

 tions in which they grow, it is surprising 

 that so many physicians should place any 

 value upon aerial disinfection in the sick- 

 room. Surely, it may be reasonably con- 

 cluded that an atmosphere sufficiently im- 

 pregnated with gases or vapors to be de- 

 structive of the spores or germs of schizo- 

 phytes, would also be poisonous to human 

 beings. 



— It is seldom that we hear anything 

 about the notices under " Exchanges," 

 and at times we have questioned whether 

 our readers were deriving benefit from 

 them. Dr. Ward's offer of pigeon-post 

 despatches, however, has, we are sure, 

 called forth many requests for those inter- 

 esting photographs ; and Mr. Cunning- 

 ham, who has offered slides of Biddul- 

 phia IcBvts, informs us that he has received 

 no less than thirty preparations in ex- 

 change. This shows that one can secure 

 a large collection of objects at a very tri- 

 fling cost, if he will mount some interest- 

 ing objects and offer them for exchange. 



Once more we state that we seldom 

 know anything about the kind of material 

 that is sent out in exchange. One must 



expect to receive some poor things among 

 the good ones, and the most we can do is 

 to urge our readers to select for exchanges 

 good material and to mount it well. 



— We are pleased to notice that the 

 Boston Society of Natural History is again 

 enabled to announce that a sea-side labor- 

 atory, under the direction of the Curator, 

 and capable of accommodating a limited 

 number of students, will be open at An- 

 nisquam, Mass., from July 1st to Septem- 

 ber 1st, 1882. 



The purpose of this laboratory is to 

 afford opportunities for the study and ob- 

 servation of the development, anatomy, 

 and habits of common types of marine 

 animals, under suitable direction and ad- 

 vice. There will be no attempt to give 

 lectures or any stated courses of instruc- 

 tion. For more definite information, ap- 

 plication should be made to the curator, 

 Mr. Alpheus Hyatt. We trust some of 

 our readers will avail themselves of this 

 opportunity to learn how to study the 

 processes of growth and development. 



Annisquam is situated on an inlet of 

 Ipswich I3ay, on the north side of Cape 

 Ann, and is about three and a half miles, 

 by coach, from the Eastern Railroad 

 Company's station in Gloucester. 



CORRESPONDENCE. 



SWARM-SPORES OF CLOSTERIUM. 



To THE Editor. — On reading the 

 article on the reproduction of Closterium 

 by swarm-spores, in the March number 

 of the Microscopical Journal, I at 

 once recognized the resemblance between 

 the figure 8 there given, and the figure of 

 Chytrtdtum endogenum, described by 

 Alexander Braun as inhabiting Closterium 

 lunula. Braun believed that the microgoni- 

 dia of Closterium, described by Focke, 

 were merely the zoospores of the Chytri- 

 dium. In the paper by Mr. Holland, he 

 states that the round bodies found were 

 green, as well as the swarm-spores them- 

 selves. In Chytridiiwi, however, there is no 

 green color, but the parasite is nearly color- 

 less. Inasmuch as the resemblance to C. 

 endogenum, is in most points surprisingly 

 great, would it not be well to inquire 

 whether there has not been some error in 

 describing the color in the JOURNAL, and 

 also the approximate number and size of 

 the zoospores, coming from a single cell, 

 W. G. Farlow. 



Cambridge, April 2ist. 



