242 THE AMERICAN MONTHLY [Aug. 



twenty-two days inclusion in the experimental bottle. 

 After immersion in the same water largely charged with 

 5 per cent of India ink for a period of either twenty- 

 four or forty-eight hours, the nuclei of all living diatoms, 

 N. nobilis, N. firma, etc., were very easily distinguished 

 in their living condition. This was on or about the 

 twentieth day of my studies ; the N. firmas seemed to 

 have absorbed the India ink around the globules and in 

 the endochrome. The frustules at this time were densely 

 packed with numerous globular masses and were quite 

 dark. It is possible that the gelatine base of India ink 

 is a food pabulum adapted to the diatoms, as it seems to 

 agree with them while aniline stains which are toxic kill 

 them. 



Microscopical Technique Applied To Histology. — V. 



[from the FRENCH OF RENE BONEVAL.] 

 Continued from Vol. XF, page 213. 

 To Examine the Marrow and the Periosteum,. — For the 

 latter no special preparation is needed, sections made aft- 

 er decalcification of a piece from the periphery of a bone 

 showing all the desirable details. To observe the ele- 

 ments of the marrow, break the femur of a young ani- 

 mal, take out a small piece of the marrow and dissociate 

 it rapidly on a slide without fluid. Expose to osmic acid 

 vapor, and stain in picro-carmine. . . . 



STRIATED MUSCULAR TISSUE. 



To study the sarcolemma, the nuclei, the fibrillsB, etc., 

 which enter into the composition of muscular tissue, we 

 should seek different animals because certain details of 

 structure are more easily appreciable in one kind than 

 in another. . .,. 



Sarcolemma. — Dissociate in water a bit of muscle 

 from the sartorius of a frog ; in a few minutes the 

 water penetrates the sarcolemma by endosmose and sep- 



