CALCIUM PHOSPHATE AND CALCIUM CARBONATE. 297 



Apparently in some of these cases at least, as Brownian movement 

 ceases and the particles grow in size, the spherule is transformed 

 directly into the crystal. 



In the degeneration of the large spherule it seems to me we have 

 a similar phenomenon to that of the other cases. The large 

 spherules could correspond to the amorphous particles of the 

 aqueous solution, fused into a large mass, the redissolving occurring 

 very late to form the final crystal. There is evidently a very strong 

 directive force toward the formation of crystals even in the col- 

 loids, and though interfered with and hindered by them for a long 

 period, it nevertheless conquers. What it is that initiates the 

 change after the deposit has remained stationary for many months 

 is problematical. There was no infection in the gelatin, no change 

 in its appearance, or any other fact to give a clue. 



Some slides in other series in both gelatin and albumen also 

 show evidence of some change in the spherules, which in view of 

 the above facts may be expected to progress farther. 



As far as I know this remarkable transformation of the pre- 

 cipitate has never been described before. The further investiga- 

 tion of this phenomenon is outside of my province and belongs to 

 the field of physics and chemistry, where it will provide some very 

 interesting problems which I hope some competent investigator will 

 undertake to solve. 



A second method of disintegration (Fig. 6) has also been ob- 

 served in a lecithin solution, where some large spherules with very 

 marked striation lost this striation after the lapse of several months 

 and became dully opaque. Certain clear radii then appeared along 

 which cleavage occurred, splitting the spherule into sectors which 

 finally separated, giving triangular crystals. 



Number of Forms Assumed by Precipitate. 

 It is to be remarked that in no slide was it possible, after Brown- 

 ian movement ceased, to obtain only a single form of deposit. 

 There were always two, and in many cases several forms occurring, 

 and this applies equally to pure aqueous and to colloidal solutions. 

 This multiplicity of form in the precipitate has also been noted by 

 Biedermann and is due doubtless to differences in the relative con- 



