46 THE AMERICAN MONTHLY [March, 



geminules ; stability or decadence during the winter ; modes of distribution 

 and progression, whether ahvays down stream or by other more adventitious 

 methods ; what becomes of the gemmules upon reaching saU water, and the 

 thousand and one problems that go to make up the life history of any animal 

 form, and that, in this instance, have been very little studied. I am particu- 

 larly anxious that some competent person should undertake their study in the 

 brinv, brackish and the fresh-water lakes, pertaining to what is kno^vn as the 

 ' Great Basin of the West,' with a special view to ascertain the conditions 

 under which they form ' protected gemmules ' in such localities. By this 

 means, light may possibly be thi-own upon the problem of their possible 

 derivation from the marine sponges. 



Great pleasure and profit mav be attained in the same direction, by germ- 

 inating the statoblasts or gemmules under artificial conditions, and studying 

 the development of the young sponges by the aid of as high po\vers of the 

 microscope as the ingenuity of each student may bring to bear upon the sub- 

 ject. I take the liberty to copy from the Ann. and Mag. Nat. His. 1882, p. 

 365, Mr. Carter's directions for germinating statoblasts, ^vhich will be found 

 valuable. 'To obtain the young spongillie it is only necessary to get a por- 

 tion of an old living specimen bearing statoblasts, and, having taken out a 

 a few (six to twelve) of the latter, to roll them gently between the folds of 

 a towel to free them from all extra materials as much as possible, place them 

 in a watch-glass so as not to touch each other, with a little water, in a saucer 

 or small dish filled with small shot to keep the saucer upright, and covering 

 them with a glass shade, transfer the whole to a window bench opposite to 

 the light. In a few days the young Spono'tlla may be observed (from its 

 white color) issuing from the statoblast and gluing the latter as well as itself 

 to the watch-glass, when it will be ready for transfer to the field of the micro- 

 scope for examination, care being taken that it is never uncovered by the 

 water, which may be replenished as often as necessary ; but of course the 

 object-glass (when j inch with high occular is used for viewing the minute 

 structure) must admit of being dipped into the water without suffusion of 

 the lens.' 



( To be continued). 



The staiuiiig of animal and vegetable tissues.* — III. 



By ARTHUR J DOHERTY, 



MANCHESTER, ENGLAND. 



NIGROSINE FOR COLORING NUCLEI OF VEGETABLE CELLS.* 



' M. Errara finds nigrosine an excellent reagent for the nuclei, which are 

 colored a very deep blue, and stand out very clearly, the rest of the cell re- 

 maining practically colorless. 



' Nigrosine is one of the derivates of tar, and belongs to the class of indulines. 

 It is soluble in water, and insoluble in alcohol and ether ; and for coloring 

 should rank with safranin, methylgreen, and other recognized agents. 



' The preparation should be placed for a short time in a solution of nigro- 

 sine, and then washed in distilled water until the water takes up no more 

 coloring matter. It can then be mounted in glycerin, or in balsam or dam- 

 mar. The former method is preferable if it is desired to study the protoplasm, 

 and the part of the nucleus formed of achromatine (of Fleming) ; the second 

 should be adopted for the examination of chromatine (= nucleine), as the 

 grains of starch which hinder observation ai^e rendered invisible.' 



* Journal Royal Microscopical Society, for 1881, p. 839. 



