1885.] NEW-YORK MICROSCOPICAL SOCIETY. 123 



DR. woodward's PHOTOGRAPHS OF DIATOMS. 



President Van Brunt attributed the excellence of Dr. Wood- 

 ward's photomicrographs to the use of the wet-plate process and 

 of sunlight. 



Mr. Dudley said that the dry-plate process, although it has 

 been greatly improved since its introduction, and is destined to 

 further improvement, will probably never render the fine lines 

 of diatoms with the precision of the wet-plate process. 



DIATOMS FASTENED BY HEAT. 



President Van Brunt : " Prof. Hamilton Smith has recently 

 sent me an excellent slide of diatoms mounted in his newest 

 medium and exempt from the mobility which drew forth criti- 

 cism at the meeting of March 20th. The diatoms were fixed to 

 the cover-glass by means of heat. When diatoms are fastened 

 by this method, only so much heat should be applied as is found 

 to be really necessary. Least heat is required when the diatoms 

 are taken from a solution of alkali." 



THE proper care AND USE OF MICROSCOPE LENSES. 



Mr. Balen : " For cleaning the lenses of my microscope, I use 

 an old silk handkerchief which has been cleansed from grease and 

 from soap, and has been made soft, after drying, by being rubbed 

 inside another handkerchief. The upper lens of the eye-piece I 

 protect from dust by keeping over it a small circular piece of 

 blue glass. It hence needs not that frequent cleaning which, 

 if care be not used, endangers polish." 



Mr. Wales, after expressing approval of Mr. Balen's method 

 of cleaning lenses, described and illustrated his own. He gave 

 also hints and cautions on the proper care and use of lenses, and 

 sketched some curious instances of their maltreatment. His 

 observations constitute the opening article in this Number of 

 the Journal. 



Meeting of April 17TH, 1885. 



The President, Mr. C. Van Brunt, in the chair. 

 Fifty-six persons present. 



observations on sponges. 

 H. J. Rice, Sc. D., who was present as a guest, gave an 

 Address, by invitation, on the subject of sponges. He treated 



