158 PROCEEDINGS OF THE 



short time, he anticipated, almost complete herbaria of British 

 phanerogamic and cryptogamic plants, and an extensive series of 

 the Invertebrata would be available to students of natural history. 

 He then proceeded to discuss the question of " Species." He con- 

 tended that at the present time, and so far as experience is con- 

 cerned, species are real entities, and that we should be able clearly 

 to separate each from the other, if all the relative physiological and 

 morphological data were mastered. He adduced many instances 

 of species of insects which had been confounded, when only known 

 in one stage of their lives, but had proved quite distinct when their 

 larvae were discovered; and of species that had been mixed together, 

 from too much attention being paid to variable characters such as 

 colour, whilst structural peculiarities were neglected. He then re- 

 ferred to the investigations of Weismann on the seasonal dimorphism 

 of butterflies and of others on the brine shrimp, as tending to 

 rectify our ideas of species, and to throw light on the causes of 

 variation. In explanation of his remarks he exhibited a series 

 of specimens illustrative of dimorphism in gall-flies and ants, and 

 of the phenomena of mimicry. 



31st May, 1881. 



Mr. Peter Cameron in the Chair. 



Mr. Peter Ewing exhibited a series of mosses from his herbarium. 

 He had made a short excursion into the Highlands a few days 

 before, and reported that alpine vegetation was this year more than 

 usually advanced by about two weeks. He had observed Saxifraga 

 oppositifolia and Silene acaulis in fine fruit at a higher elevation 

 than the snow patches still left. He could only attribute this to 

 the persistent and unbroken coating of snow which had protected 

 the plants all winter. 



The Chairman exhibited the gall and both sexes of Spatlwgaster 

 verrucosus from Mugdock Wood. The galls are found on the leaf- 

 buds of the oak, three or four on each, and frequently on the young 

 leaves. This species has not been previously recorded for Scotland. 



Professor A. S. Wilson, M.A., B.Sc, read a paper entitled "The 

 Morphology of Underground Stems," in which he explained the 

 true relations of these organs. In every respect these underground 

 structures agree with ordinary leaf -forming axes, and the same law 



