162 Transactions of the Society. 



It has to be put into hardening and water-absorbing solutions, 

 then to be cut with microtomes, perhaps frozen in the first instance, 

 then to be put into other solutions to be cleared and to have its fat 

 got rid of, and then it has to be coloured once, twice, or thrice, and 

 possibly to have some colour discharged. I'inally it has to be 

 mounted in a medium. It is necessarily somewhat deterrent for a 

 modest microscopist to read the excessively pronounced opinions of 

 manipulators, about the nature of the structure they discover in 

 such complicated and altered organic matter, and to find that very 

 contradictory opinions are published by different investigators about 

 the nature of identical structures which have been differently 

 prepared. It appears to many an amateur, who happens to in- 

 vestigate structures by disturbing their natural condition as little 

 as is possible, that he is, as it were, out of the field. He may find it 

 necessary, even in examining the simj^lest section, to pay especial care 

 to the illumination and centering, and to the application of particular 

 powers. He is, of course, conscious of inferiority, when he knows 

 that somebody merely puts a chemically treated specimen under an 

 objective without the least care about optics, and finds out, or 

 thinks he finds out, the truth. But there are numerous oppor- 

 tunities for original research still to be met with in the structure 

 of many of the commonest invertebrates and plants. The study 

 of rocks is in its infancy, and there are many very interesting 

 physical questions yet to be determined, and which can only be 

 settled microscopically. Kecondite manipulation is not much 

 required in any of these researches, but rather a good knowledge 

 of how to use the Microscope as an instrument. 



If in any case there are obstacles to original research, it is 

 always interesting to follow the work of some distinguished in- 

 vestigator. It is very rarely that a subject is treated exhaustively, 

 and the sedulous yet candid critic, may solve truths which his 

 predecessor had not approached. 



In concluding this address, I cannot avoid a special mention of 

 the recent death of a man whose genius and careful microscopical 

 work, estabUshed an era in histology, and influenced that study of 

 embryology which must ever be the starting point of philosophical 

 zoology and botany. Theodore Schwann elaborated the "cell 

 theory " forty-thi'ee years ago, and in the main it holds good at the 

 present day. He lived to see its value appreciated by every zoologist, 

 and to be able to follow the researches with improved lenses, and to 

 recognize the entities which have no cell-wall. Schwann investi- 

 gated most successfully the nervous system, and his name will 

 ever remain associated with it. He died at a ripe old age, having 

 led an industrious, simple, and most useful life, and having lived to 

 see himself the recipient, on the occasion of his jubilee, of distin- 

 guished honours on the part of the scientific world. 



