30 Prof. B. Moore. The Production of Growths or 



experiments of the preceding paper with the same reagents, but with care 

 fairly well developed networks of fibres may be obtained by this method. 



The next method employed was that of mixing two colloidal solutions of 

 opposite cataphoresis (or electrical sign of the colloid), until the point of 

 permanent precipitation was just being approached. The pair of colloids first 

 tested consisted of colloidal ferric hydrate and colloidal silicic acid, each 

 prepared by Graham's method. The two colloidal solutions used were 

 freshly prepared and, when examined microscopically before admixture, were 

 found to be free from fibrils. 



In a series of test-tubes varying volumes of the two colloidal solutions were 

 then mixed together, so as always to yield a constant total value of 10 c.c, 

 and the mixture in each case was immediately shaken up and allowed to 

 stand. Thus, in the experiment from which the microphotographs shown in 

 Plate 2, fig. 1, were obtained, a series of tubes were prepared as follows : — Tube 

 No. 1, 9 c.c. colloidal ferric hydrate plus 1 c.c. colloidal silicic acid ; tube 

 No. 2, 8 c.c. colloidal ferric hydrate plus 2 c.c. colloidal silicic acid ; tube 

 No. 3, 7 c.c. colloidal ferric hydrate plus 3 c.c. colloidal silicic acid, and 

 so on. The colloidal ferric hydrate contained 0136 per cent, of Fe203, and 

 the silicic acid approximately - l per cent, of Si02, and the above experi- 

 mental procedure demonstrated that the best admixture for the rapid 

 production of fibrous growths was 8 c.c. of the colloidal ferric hydrate solution 

 to 2 c.c. of the colloidal silicic acid solution. 



When mixed in these proportions and then in a few minutes examined 

 under the microscope, magnificent networks are seen which are stained a pale 

 yellow colour in the coarser fibres. Some of the fibres are so delicate and 

 fine that they are only visible with a high magnification and using diminished 

 illumination. Others, such as those shown in the microphotographs of fig. 1, 

 are coarse and easily visible with the low power. Photography of these 

 products is exceedingly difficult, and gives but a poor impression of the net- 

 works as seen under the microscope. Some of the medium-sized fibrils are 

 double contoured, they branch, and in many cases show nodulation, cross 

 striations, or divisions. In fact, many of the appearances presented by growing 

 hyphse are closely simulated. 



It has not been possible for me to observe the mode of growth of these 

 fibres. Large numbers are present almost at once when the two colloidal 

 solutions are mixed, for the mixed solution examined straightway with the 

 microscope shows them from the commencement. On careful examination 

 of a freshly mixed preparation microscopically, with the greater part of the 

 illumination cut off, and a magnification of about 400-500 diameters, 

 exceedingly delicate networks and long branching fibrils may often be just 



