160 NOTES AND MEMOUANDA. 



Merostoniata. If, however, the Trilobites have true walkiiifj- 

 legs instead of mouth-feet (gnathopodites) only, they would 

 be more closely related to the Isopoda. He showed by a 

 tabular view of the Arthi'opoda that the known range in 

 time of the great classes is nearly the same, and therefore 

 aflfords no argument for combining the Merostomata with 

 the Arachnida; but on the contrary, he considered that the 

 Trilobita were, with the Entomostraca, the earliest repre- 

 sentatives of the class Crustacea, and could not therefore be 

 removed from that class. — {Nature.) 



The Asci in Peziza. — Having left a specimen of Peziza 

 humosa for a long time in water, until it became quite soft 

 and pulpy, I was curious to examine it in such condition, and 

 found that the hymenium presented a singular appearance. 

 All the paraphyses had become dissolved into a granular mass, 

 retaining still some of their original colour. Amongst these 

 the asci were free, and there Avere some free sporidia. In 

 their normal condition the asci are cylindrical, and the 

 sporidia are arranged in a single series ; but in the present 

 case the asci had become perfectly s[)herical, from the 

 absence of all lateral pressure, and the sporidia were clus- 

 tered in the centre. The line of the external surface of the 

 asci was very distinct amongst the orange-tinted granular 

 mass, and the eight sporidia could be counted within. There 

 could be no doubt of the presence of an investing membrane, 

 but of a much more elastic nature than has been supposed. 

 This fact seems to suggest the probability that more or less 

 lateral compression in the hymenium may influence the 

 character of the asci, and that cylindrical, or clavate and 

 elliptical asci, indicate more or less lateral pressure during 

 development. — (M. C. C, in Nature.^ 



Carmine Tinting of Objects hardened in Chromic Acid. — 

 It is well known that tissues which have been long hardened 

 in chromic acid are coloured by carmine solution with great 

 difficulty, and sometimes very imperfectly. The following 

 method, given in the preface to the last part of Henle's 

 'Anatomy,' has been invented by Merkel to obviate this 

 difficulty, in the case of preparations of the nerve-centres. 

 By means of it an object may be perfectly tinted in five 

 minutes, which would by the ordinary method require 

 twenty-four hours. The section, when thoroughly deprived of 

 water, is placed in a solution of chloride of palladium in 300 

 or 600 parts of water. In this it is allowed to remain long 

 enough to acquire a pale yellow or straw colour, which takes 

 one or two minutes. The excess of palladium solution is 

 ^ then washed out, and the section placed in a somewhat con- 



