HARDWICKE'S SCIENCE-GOSSIP. 



67 



that entomology often afforded valuable evidence as 

 to the progress of geographical distribution, the 

 insects which affect the eucalyptus in Australia not 

 having accompanied it on its introduction into 

 Europe. He claimed that entomology was the 

 chief attraction in the greatly increasing number of 

 naturalists' societies and field clubs ; and that the 

 study was not only useful, but very popular, pro- 

 viding a civilising and refining recreation for many 

 dwellers in towns. Referring to the vast scope of 

 this field of study, he accepted Dr. Sharp's estimate 

 of 2,000,000 existing species of insects, of which 

 about 200,000 are described. At the present rate 

 of 5)6oo annual additions, it would take 340 years to 

 complete the lists. During twenty-four years of 

 the publication of the " Record of Zoological 

 Literature," 42^ per cent, of its pages had been 

 occupied with entomology. In the " Biologia 

 Centrali Americana," dealing with the whole 

 terrestrial fauna of a district of 900,000 square miles, 

 30,000 species of insects would be recorded, of which 

 43 per cent, are new, all other branches of zoology, 

 exclusive of spiders and land -shells, producing only 

 •937 species, less than 5 per cent, being new. 

 Noticing the rich collections in the British Museum, 

 he pointed out that after recent changes only six 

 regular entomologists were now employed to classify 

 and arrange some 20,000 annual additions, to attend 

 to visitors and students, and to describe novelties, 

 always keeping up a knowledge of the vast literature 

 of the subject ; whereas the authors of the 

 " Biologia " had to employ twenty-two specialists on 

 entomology alone, seven only for all other branches 

 of zoology. He regretted that the public funds 

 available were insufficient to provide a much larger 

 staff, or to form a separate department. 



BOTANY. 



Autumn Colours.— Professor J. H. Pellsbury 

 has the following remarks on autumn colours in the 

 last number of " The American Monthly Micro- 

 scopical Journal " : — " In addition to the chlorophyll 

 of plants, there is generally present in their cells a 

 small quantity of certain other colouring matters, as 

 xanthophyll, erythrophyll (yellow and red colouring 

 matter), both of which are derived from chlorophyll 

 by the chemical forces of the plant, but which are in 

 so small proportions as to be more or less completely 

 covered up by the presence of the chlorophyll. If 

 from any cause these are increased in quantity, they 

 give their peculiar colour to the leaves, as is the case 

 with foliage plants. In the normal growth of the 

 plant, especially of perennial plants like our forest 

 trees, the early summer is the period of rapid growth. 

 Later in the season the cells formed in the early 

 summer become hardened into wood, and active 

 growth ceases. At this time the portion of the 



chlorophyll is changed to xanthophyll and erith- 

 rophyll, and a portion withdrawn to other parts of 

 the plant. This leaves the bright colours in sole 

 possession of the cells, and gives the peculiar tints 

 to the autumnal leaves. These changes are affected 

 by the variations of the season. When the season is 

 very dry the nutrition of the plant is interfered with, 

 and the growth ceases at an abnormally early date, 

 and the colours make their appearance earlier than 

 usual, but are less brilliant. Early frosts destroy the 

 life of the leaf, and prevent the brilliancy of the 

 colours. A great degree of moisture seems also to 

 produce early changes. During the past very wet 

 season in New England the leaves of maples in wet 

 grounds showed bright colours early in August. A 

 medium amount of moisture and late frost seem to be 

 favourable to the greatest brilliancy in leaves. The 

 colours of flowers and fruits are due to similar 

 changes in which other colouring matter of a slightly 

 different chemical composition is produced. The 

 chlorophyll of the green flower or fruit is changed 

 into a special colouring matter. This in the case of 

 yellow flowers is anthoxanthin ; of white flowers, 

 anthaleucin ; of blue flowers, anthocyanin, &c. 

 These changes are produced as the fruit matures, or 

 the flower opens. Violet and purple tints are pro- 

 bably due to the action of acids in the cells upon 

 their colouring matters. The fall of the leaves is 

 due to the peculiar structure of the leaf petiole. A 

 .ayer of rather large cells at the union of the petiole 

 with the stem of the plant is deprived of some of its 

 nourishment, whereby its walls remain thin, and the 

 protoplasm becomes at length dried or killed by 

 frost, when the cells shrivel and break, and the leaf 

 having nothing to support it falls to the ground. 



Monstrosity of Hyacinth. — Early in January, 

 I had a double pink hyacinth grown in water in 

 flower. One of the flowers consisted of two flowers 

 united throughout. The stalk exactly resembled two 

 stalks joined together. •• The twin ovaries were dis- 

 tinctly visible. On dissection, I found the ovaries 

 small but quite perfect with separate styles. There 

 were thirteen stamens. Is this kind of monstrosity 

 common ? Although rather early, the plant had not 

 been in any way forced. Is it likely to occur next 

 year in the same bulb ? — H. J. Perretl, Famham, 

 Surrey. 



Erodium maritimum. — On June 9th, 1889, I 

 found this plant growing on a bridge that crosses 

 the Trent, at Little Haywood, near Stafford. This 

 bridge was built in 1887-8, so I thought it must have 

 been brought there with the ballast. On November 

 24th, 1889, 1 ascertained that the gravel was dug from 

 some pits on Cannock Chase, about half a mile away. 

 I visited these pits, and found a large number of 

 plants of Erodium maritimum growing in two places 

 where the sandstone and conglomerate rocks have 

 been laid bare, on the east slope of a low range of 



