416 



A New Form of Specti*oscope. 



[Dec. 17,. 



spores were floated on the surface of the fluid, but I had not suc- 

 ceeded in finding evidence of growth when the hairs were submerged. 

 This result must have been due to some accidental cause which 

 escaped undetected, as I have found that trichophyton grows when the 

 hairs are entirely submerged in the gelatinised beef juice, and the 

 spores are excluded from contact with the air. 



In my previous paper I described a number of experiments which 

 appeared to show conclusively that trichophyton is not related to the 

 ordinary fungi (^Penicillium, Mucor, &c.) with which it had been up to- 

 that time confounded. The experiments with gelatinised meat juice 

 confirm that view. In many instances in which I cultivated tricho- 

 phyton on this medium I never once observed organs of fructification 

 or appearances that suggested that it could be identified with common 

 fungi. As regards Penicillium glaucum with which, from the abund- 

 ance of its spores in the atmosphere of laboratories, cultivations are 

 most likely to be, and are most often fouled, the difference can be 

 shown by a very simple experiment. 



A layer of the gelatinised meat juice is poured over a pure slide 

 and allowed to cool under proper precautions. Ringworm hairs and 

 penicillium spores are " sown " in parallel lines on the surface of the 

 medium, and the slide is put in a moist chamber at ordinary tempera- 

 tures. If the slide is examined in from twenty-four to forty-eight 

 hours the penicillium will be found to be growing with great rapidity, 

 whilst the mycelium of trichophyton has made in comparison very 

 little growth. Repeated crops of penicillium may be grown up to the 

 stage in which the characteristic organs of fructification are fully 

 developed, whilst during the same time the trichophyton mycelium 

 grows steadily and slowly, with no distinct signs of spore formation 

 and no trace of organs of fructification. 



I may add that, in a recent letter to me, Dr. Koch states his convic- 

 tion that trichophyton is a distinct and independent kind of fungus. 



IV. fc< A New Form of Spectroscope." By J. Norman Lockyer,, 

 F.R.S. Received December 5, 1885. 



Some two or three years ago, when the sun-spot work carried on 

 at Kensington revealed the different behaviour in different spots of 

 lines visible in the spectra of the same element, it seemed desirable 

 to extend similar observations to metallic prominences, and, if 

 possible, in such a way that comparisons over a considerable reach of 

 spectrum should be possible. 



It then struck me that a grating cut in half, with one part movable, 

 would afford a ready means of doing this. 



