230 The Naturalist of Cumbrae. 



strongest proof of its power of endurance was when 

 under the microscope for examination, placed on a 

 flat piece of glass often from ten to twenty minutes 

 at a time, and yet when dropped into the water it 

 would dart off, making one or two evolutions, and 

 disappear in the gravel, to all appearance little the 

 worse for the unnatural exposure. I may, however, 

 mention that sometimes after examination, when 

 returned to the water it would sink down and lie for 

 some few minutes on the gravel in a mbtionless state, 

 as if it were dead. But this it often did in the water, 

 when repeatedly poked out of the gravel in which it 

 always, by preference, lay concealed. 



" We all earnestly hope that you will try and force 

 a point to come by Glasgow on your journey, and 

 with some time on your hands. Could we not drop 

 a note to Limulus to lay her eggs at the suitable 

 time? 



" Mrs. Robertson and the boys are gratified by the 

 cheers. Be assured of all our warmest regards and 

 well wishes. 



" Yours very truly, 



" DAVID ROBERTSON. 



" Since writing the above, your paper on the 

 ' Morphology of the Arthropoda ' is to hand, for 

 which accept my thanks. Although only in the 

 embryonic state, yet all its parts are well defined, 

 and it is full of elements of large development." 



To explain some of the allusions in this letter, it 

 should be remarked that Dr. Dohrn was at this time 

 anxious to study the development of the young of 



