ADDRESS. 7 



preservation of the whole. The organs are, as it were, special machines 

 situated in the general building which constitutes the factory or body 

 of the individual. But, further, each organ or special machine is itself 

 formed of tissues which possess different properties. Some, as the blood- 

 vessels, nerves, fibrous tissues, &c., are generally distributed throughout 

 the animal body, whilst others, as bones, muscles, cartilage, tfcc, are found 

 only in certain definite localities. Whilst Bichat had acquired a definite 

 philosophical conception of the general principles of construction and of 

 the distribution of the tissues, neither he nor his pupil Beclard was in a 

 position to determine the essential nature of the structural elements. 

 The means and appliances at their disposal and at that of other ob- 

 servers in their generation were not sufficiently potent to complete the 

 analysis. 



Attempts were made in the third decennium of this century to improve 

 the methods of examining minute objects by the manufacture of com- 

 pound lenses, and, by doing away with chromatic ;ind spherical aberra- 

 tion, to obtain, in addition to magnification of the object, a relatively large 

 flat field of vision with clearness and sharpness of definition. When in 

 January 1830 Joseph Jackson Lister read to the Royal Society his 

 memoir ' On some properties in achromatic object-glasses applicable to 

 the improvement of microscopes,' he announced the principles on which 

 combinations of lenses could be arranged, which would possess these 

 qualities. By the skill of our opticians, microscopes have now for more 

 than half a century been constructed which, in the hands of competent 

 observers, have influenced and extended biological science with results 

 comparable to those obtained by the astronomer through improvements 

 in the telescope. 



Tn the study of the minute .structui'e of plants and animals the observer 

 has frequently to deal with tissues and organs, most of which possess such 

 softness and delicacy of substance and outline that, even when micro- 

 scopes of the best construction are employed, the determination of the 

 intimate nature of the tissue, and the precise relation which one element 

 of an organ bears to the other constituent elements, is in many instances 

 a matter of difficulty. Hence additional methods have had to be devised 

 in order to facilitate study and to give precision and accuracy to our 

 observations. It is difficult for one of the younger generation of biologists, 

 with all the appliances of a well-equipped laboratory at his command, 

 with experienced teachers to direct him in his work, and with excellent 

 text-books, in which the modern methods are described, to realise the 

 conditions under which his predecessors worked half a century ago. 

 Laboratories for minute biological research had not been constructed, 

 the practical teaching of histology and embryology had not been organised, 

 experience in methods of v/ork had not accumulated ; each man was left 

 to his individual efforts, and had to puzzle his way through the complica- 

 tions of structure to the best of his power. Staining and hardening 



