1892-93-] Recent Work by Dr J. M. Macfarlane. 63 



Pennsylvania, at Philadelphia. His loss is a great one to 

 Britain as well as to our Society, — a great gain to his adopted 

 country. In memory of old times he has sent me some of 

 his recent papers. He has lately published a most valuable 

 paper on Dionaea muscipula, a common insectivorous plant of 

 North Carolina. Hitherto all observers (except Dr Burdon 

 Sanderson) have erroneously stated that the leaf of this plant 

 closes if you touch one of the leaf-hairs. Dr Macfarlane has 

 shown that this is not correct, and that Dr Burdon Sanderson 

 was right in saying that two hairs must be touched, or that 

 one hair must be touched twice. This is analogous to tetanic 

 contraction of a human muscle. The protoplasm of the leaf 

 seems to retain memory of the first touch for about forty 

 seconds. The first touch does not close the leaf, but prepares 

 it for rapid closure should a second touch occur within half a 

 minute or so. Dionsea, like Drosera, is not affected by rain- 

 fall. If a stimulus continues to act on it, as occurs when an 

 insect is grasped, a secretion is poured out from special glands 

 which digests the captured insect. This secretion is acid to 

 litmus paper, and if coagulated by alcohol appears amoeboid 

 under the microscope. 



Another paper by Dr Macfarlane is on his favourite sub- 

 ject — Hybridisation. Amongst several other plant - hybrids 

 the peculiar characteristics of which, as derived from the 

 parents, he has demonstrated, Dr Macfarlane studied, with 

 praiseworthy skill and labour, a hybrid produced by crossing 

 Lapageria rosea % with Philesia buxif olia £ . The two plants, 

 though not very like, belong to the same natural family. In 

 the hybrid thus produced Dr Macfarlane found the charac- 

 teristics of the male and female parents curiously blended in 

 habit, foliage, and flower. If anything, the vegetative organs 

 of the hybrid were more like those of its male parent, and the 

 reproductive organs more like those of its female parent. As 

 a whole, the hybrid was vegetatively superior to either parent. 

 Eeproductively, it was inferior to both, — the pollen cells 

 especially looking starved. 



Dr Macfarlane's general conclusions on this interesting 

 subject of hybridisation are — (1) Most hybrids are almost 

 exactly half - way between their parents. (2) Structures 

 peculiar to either parent are represented halved in the hybrid. 



