ITS CHEMICO-PHYSICAL AND MORPHOLOGICAL PROPERTIES 41 



as a rule, towards the staining substance united to it, like a wealdy 

 alkaline body " (Fol). 



Further, nuclein exhibits characteristic chemical reactions, 

 which must not be forgotten in preparing nuclear structures for 

 preservation (Schwarz II. 37, Zacharias II. 43, 45). It swells up 

 in distilled water, in very dilute alkaline solutions, and in 2 or 

 more per cent, solution of common salt, of sulphate of magnesia, 

 or of monopotassium phosphate and of lime-water. If solutions 

 of from 10 per cent, to 20 per cent, of the above-named salts are 

 used, the nuclein, whilst swelling gradually, becomes quite dis- 

 solved. Similarly, it dissolves completely in a mixture of ferro- 

 cyanideof potassium and acetic acid, or in concentrated hydrochloric 

 acid, or if it is subjected to pancreatic digestion. It becomes pre- 

 cipitated in a fairly unaltered form if treated with acetic acid 

 from 1 to 50 per cent, in strength, when it can be very clearly 

 distinguished from the protoplasm by its greater refractive power, 

 and by a glistening appearance which is peculiar to it. 



FIG. 20. A resting nucleus of a spermato-genetic cell of Ascaris megalocephala 

 bivalens. B Nucleus of "a sperm-mother-cell from the commencement of the growth-zone 

 of Ascaris megalocephala bivalent. C Resting nucleus of a sperm-mother-cell of the growth 

 zone of .Ascaris megalocephala hivalens. D Bladder-like nucleus of a sperm-mother-cell of 

 .Ascaris megalocephala bivalens, from the commencement of the dividing zone, shortly 

 before division. 



In the nuclear vesicle (Fig. 20), the nuclein sometimes appears as 

 isolated granules (A), or as delicate network (B, 0), or as threads (D). 



Miescher (II. 49) has attempted to obtain pure nuclein from 

 pus corpuscles and from spermatozoa, in the heads of which it is 

 present. An important ingredient in its composition is phosphoric 

 acid, of which at least 3 per cent, is always present. Several 

 facts seem to indicate that the nuclein of the nucleus " consists of 

 a combination of an albuminous body with a complex organic com- 

 pound containing phosphoric acid (Kossel II. 35). This latter has 

 been called nucleic acid, and Miescher has calculated its formula 

 to be C 29 H 49 N 9 P 3 22 . 



" If subjected for a long time to the action of weak acids or 

 alkalies, or even if kept in a damp condition, nuclein becomes de- 



