Royal Microscopical Society. 101 



and lampblack make the best cake of this kind, and the object can 

 be fastened on to it with pins. The dissection is made by fine 

 needles, mounted in small holders. It is anxious work, and is done 

 with the help of a pocket glass. Of the smallest embryos, portraits 

 have to be taken of very perfect specimens which have not become 

 shrunken in the spirit. These are of great value, as they show the 

 form and relations of the principal masses of the skull and face. 

 They also serve as a platform on which the mind can place what it 

 has discovered of the structure of the parts as displayed by sections. 

 After the embryos have grown somewhat, and bone begins to appear, 

 they can still be treated like the smallest, for the first traces of 

 bone do not turn the razor. These early traces of bone are of a 

 rich crimson colour in specimens that have been coloured with car- 

 mine. In larger specimens, the heads must be placed in a weak 

 solution of chromic and nitric acids ; this acid must be much 

 stronger, and be used for a much greater time, because of the 

 solidity of the bone. These larger specimens make very valuable 

 thick sections to be used as opaque objects, and with a low power ; 

 and each face of a slice, ith or ^h of an inch in thickness, shows 

 something fresh, so that each object is practically double. Perfect 

 sections of the heads of embryos taken from snout to occiput verti- 

 cally, are of great value ; a very fine saw has to be used for this 

 purpose on the older ones. The section should be made a little to 

 the left, so as not to injure the septum of the nose. Bird's-eye 

 views of the skull-floor are taken from unroofed preparations ; these 

 are very valuable, but they require extreme care in dissection, and 

 all the landmarks have to be observed and drawn, the nerves, 

 arteries, veins, muscles, and the like. Then there are lower and 

 lateral dissections to be made, so that no stone be left unturned in 

 the elucidation of the problem of the growth of the skull. Now, it 

 will be clearly seen that such a thorough root-and-branch sort of 

 work as this gives the worker no easy task ; it is such as does not 

 admit of being hurried ; but once done, it serves as a felled opening 

 in a large wood ; and when such a space is connected with similar 

 cleared spaces, a survey can be made of what was tangled and dark 

 enough at first, but which makes fine fields when well tilled. 



I cannot give you an abstract of results ; everything is in pro- 

 gress, and nothing finished ; moreover, it is natural to us to delight 

 in unfinished works, but the objects at which we labour are all 

 perfect ; completeness, beauty, and unity are stamped upon them all. 



How the unity has arisen I do not pretend to say ; if all organic 

 forms have become evolved from one common parental protoplasm, 

 the planting and stocking of this planet has been a slow business : 

 I more than suspect that there has been an overruling Will : and 

 that the whole was foreordained. 



