102 JOURNAL OF THE [April, 



gus, the Tormina clavulata, which had destroyed a coccus, of 

 the genus Lecaniu7n, and had sent up through the shell of its 

 host several stems of infioresence. He described and illustrated, 

 besides, two other species of Torrubia which are parasitic on 

 injurious insects ; and he touched the topic of the service which 

 such fungi might, if their life-history were better known, be made 

 to perform as insecticides. His observations are given in full 

 elsewhere in this Number of the Journal. 



PHOTOGRAPH OF AMPHIPLEURA PELLUCIDA. 



Mr. Mead : " The photograph of Amphipleura pellucida which 

 I have here, was loaned to me for this exhibition by Mr. R. 

 Hitchcock. It shows the dots. It was taken by Dr. Henri Van 

 Heurck, with the use of incandescent light, vertical illuininator, 

 and a Ath-inch Zeiss homogeneous-immersion objective." 



The President : " This photograph shows both sets of lines 

 clearly. It was taken, I have been informed, from a silvered 

 frustule." 



DIATOMS MOUNTED IN PROF! SMITH's NEWEST MEDIUM. 



President Van Brunt : " Prof. H. L. Smith, as you all know, 

 has made a series of experiments in order to discover the best 

 material for mounting diatoms. He at length found a medium 

 which brought out the markings of diatoms very distinctly, but 

 it did not last well — it would soon cloud or crystallize. As the 

 result of further trial, he now has a medium which, he says, does 

 not crystallize. It is glycerine holding a salt in solution, and 

 has a refractive index of 1.8. I have here a dozen or more slides 

 of diatoms mounted in this material. The markings show quite 

 as well as in any other medium of high refractive index. I do 

 not, however, think that a medium of high index is suitable for 

 any but the most minute and delicate diatoms — diatoms which 

 are not easily seen under the ordinary conditions. The large 

 forms, when mounted in this medium, appear quite dark, and 

 almost opaque." 



PHOTOGRAPHS OF DIATOMS. 



President Van Brunt : " I have brought for exhibition a num- 

 ber of photographs of diatoms that were mounted in Prof. Smith's 

 new medium. They were taken by Mr. Febiger, of Wilmington, 

 Del., to whom, for this purpose, I sent my own box of slides. 



