OP ARTS AND SCIENCES, 137 



inner circle (a). Thus are these dots described and illustrated, by 

 Mohl, Schleiden, and Schacht, as seen in the common European Pine 

 [Pinus sylvestris), and thus did they always appear to me, not only in 

 that species, but also when I observed them in Pinus Strohus, except 

 with this difference, that the perforation was bounded by an exceed- 

 ingly faint third circle (C, c), whose relations I could nof comprehend, 

 nor was I able to I'econcile its presence with the theory in regard to 

 the nature of the perforation. I therefore left it, doubtingly supposing 

 it to be some optical illusion. The microscope which I used, and 

 which I have been in the habit of using up to within the last six 

 months, is an Oberhaeuser's, made for Professor Agassiz some years 

 ago ; and yet at this very day I find it as good, with perhaps a single 

 exception, as any now made in Germany, and therefore just as trust- 

 worthy in the investigation of the glandular dots of the Pine.* 



'* It may not be uninteresting to state here, that the first great microscope made 

 in Germany was constructed in 1 829 by Fraunhofer, for Professor Agassiz. This 

 microscope was represented in a copper-plate engraving, and described by Dollinger 

 in the Memoirs of the Munich Academy for 1829, or 1830. In January, 1831, 

 Agassiz went to Paris, and having given unlimited orders to Oberhaeuser for the 

 best microscope that could be furnished, according to the knowledge of those times, 

 he received from that maker, in 1832, an instrument which has not been surpassed 

 in all Germany to this very day ; at least, I have never seen any work from the 

 hands of the best observers there, whether zoologists, histologists, physiologists, or 

 botanists, which could not have been accomplished just as well by this microscope. 

 There may be one exception to this of a very recent date, but I am acquainted with 

 the instrument only through i-eport. With this masterpiece of Oberhaeuser Agas- 

 siz has gone ou to this time, doing his great work with remarkable success, as all 

 the world knows. Of late years it has become evident to Agassiz that his instru- 

 ment was not equal to the demands which the progress of his researches put upon 

 it ; that there was something beyond its reach, of which he now and then could get 

 a glimpse, just enough to warrant him in the belief that the study of the intimate 

 structure of organized bodies had hardly begun. 



So long ago as 1852 he had opportunities to see the workings of an instrument 

 of the English pattern, made by Spencer; and although it was known as a rival, if 

 not superior to the Transatlantic microscopes, he did not become convinced that 

 it came up to his requirements. 



Two or three years later I had the pleasure of bringing to his notice the results 

 of some of my own researches upon the value of recently constructed objectives of 

 English make. This gave him renewed hope, and, having heard of Spencer's con- 

 tinued rivalship and growing superiority, he determined to test his skill to the ut- 

 most. He therefore, in 1857, requested me to visit Canastota, in order to consult 

 Spencer, and advise him as to the nature of the work for which we wished to use 

 VOL. IV. 18 



