IMPERFECT MODERN MODELS 



163 



lifting ami lowering the entire weight of the body, with its coarse ad- 

 justment, lenses, and so forth ; while the sole object of the adjustment 

 should be to give a delicate, almost imperceptible, motion to the 

 object-glass alone. It needs no great experience to foresee the inevi- 

 table result ; the screw loses its power to act, and something incom- 

 parably worse than a tolerable coarse adjustment is left in its place. 



Yet it is the Con- 

 tinental model that 

 has become the dar- 

 ling of English labo- 

 ratories, and that still 

 receives the appreci- 

 ation of professors 

 and their students. 

 True they answer in 

 the main the purposes 

 sought the exi- 

 gencies of a limited 

 course of practical in- 

 struction. But how 

 many of those who 

 receive it are the 

 medical men of the 

 future, and to whom 

 a microscope not of 

 necessity a costly one 

 of the right con- 

 struction would be 

 of increasing value 

 through a lifetime ? 



Almost any in- 

 strument, however 

 inferior, could be em- 

 ployed successfully 

 with a ^-inch object- 

 ive of ' low angle ' (to 

 give it what has been 

 called ' the needful 

 penetration' for his- 

 tological subjects !) to 

 obtain an image corresponding to a figure in a text-book of, say, 

 a Malpighian corpuscle, or a section of kidney, brain, or spinal cord. 

 The quality of a fine adjustment is never tested by these means, 

 for, in point of fact, a delicate fine adjustment is not even necessary. 

 We write in the interests of microscopical research. It certainly 

 may be taken for granted that the end sought is not simply to use 

 the microscope to verify the illustrations of a text-book, a treatise, 

 or a course of lectures ; without doubt it is a subsidiary purpose ; but 

 the larger aim is to inspire in the young student confidence, 

 enthusiasm, and anticipation in the methods and promise of histology 

 and all that it touches. But for this there must be potentiality (with- 

 it 2 



FIG. 125. Ross-Zentmayer model (1878). 



