18 PROGRESS OF MICROSCOPICAL SCIENCE. 



surfaces, which are in contact with other bones (vertebral diajDhyses, 

 tarsus, carpus, sternum). (/) All epiphyses which touch an articu- 

 lation grow most at the extremity touching the articulation, (g) Those 

 parts of bones that are covered with cartilage, and are not in con- 

 tact with other bones, show a rather good growth. (The edges of 

 tlie vertebral epiphyses, the lateral parts of all epiphyses.) (h) The 

 thickness of the cartilage, whose cells are in the act of proliferation, 

 stands generally in relation to the energy of the growth of the bone 

 in length. There are, however, certain exceptions (vertebral apo- 

 physes). In the last paragraph of this paper Kolliker produces a new 

 diagi'am for exidaining the growth of long bones. 



The Micro-spectroscope in Germany. — This instrument has been 

 most employed in England ; indeed, in Germany it is not much used 

 in researches on colouring-matter. Still, that it has been used, and 

 that well, in other countries, is proved by the fine work of Dr. Gregor 

 Kraiis on chloixDphyll, &c., which has been favourably reviewed in 

 the 'Academy' by no less a person than Mr. H. C. Sorby, F.RS. 

 Mr. Sorby says : — " In studying this subject I have been more and more 

 convinced of the importance of distinguishing the various constituents 

 of complicated mixtures, and my own knowledge has to a great extent 

 advanced in the same proportion as I have been able to discover 

 methods which could be employed with advantage in deciding whether 

 a coloured solution was or was not of compound nature, and in deter- 

 mining the character of the different constituents. I have therefore 

 paid very particular attention to this question, and have been led to 

 a somewhat peculiar use of bisulphide of carbon, alcohol, and w^ater, 

 in various proj)ortions, in order to separate the constituents more or 

 less perfectly, and also to the employment of what I have named 

 photocliemical analysis, being the use of light as a reagent to decom- 

 pose some of the coloured constituents and leave others, when it is 

 difficult, or even impossible, to separate them by chemical methods. 

 Anyone who has not tried them would scarcely believe what can be 

 done by the use of such simple means. The application of these 

 methods, and the comparison of the coloured constituents of all the 

 leading classes of plants, especially those of fungi, lichens, and algse, 

 growing in various conditions, have led me to find that there is a 

 considerable number of what may be called fundamental colouring- 

 matters, which are absent or occur in very different proportions in 

 different kinds of plants, and also in the same kind, when growing in 

 different circumstances, besides a still larger number of apparently 

 unessential coloured substances, which may be present or absent with- 

 out materially interfering with the healthy growth of the plant. I have 

 given a general account of these researches in a paper recently read at 

 the Royal Society, on ' Comparative Vegetable Chromatology,'* and need 

 not describe them now ; but the results derived from these methods lead 

 me to differ from the author in some imjiortant and fundamental par- 

 ticulars. In some cases preparations which he Icoks upon as different 

 substances are in my opinion the same, only in one instance mixed 



* The number of the ' Proceedings ' in which tliis jjaper appears has not yet 

 been piiblisliod — we shall nofioe it wlion it has. 



