252 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Of tliese he describes mainly the phenomena in question in Eanuncn- 

 lacesB (^Ranunculus auricomus, BatracMum aquatile, Clematis recta, Thalic- 

 trum aquilegifolium, Adonis vernalis, and Aquilegia), Malvaceae (^Alcea 

 rosea, Malva sylvestris), and Eosaceae (^Sorbiis, Rosa, ChimonantJius, 

 Spiraea, Prunus, Potentilla). In the Eanunculacese the stamens bend 

 from a joint-like zone at the foot of the filament ; in the Malvaceae 

 this zone lies in the middle of the filament ; while in the Rosacese there 

 is a nearly uniform bending of the entire filament. This spontaneous 

 movement is a frequent phenomenon in polyandrous actinomorphic 

 flowers ; its purpose being either to place the anthers with their fissures 

 round the nectary, or, at the end of the period of flowering, in contact 

 with the stigma. 



Next follows a discussion of actinomorphic flowers with two rows 

 of stamens, including Allium (especially A. ursinmii), Caryophyllaceas 

 {Stellaria and its allies, Diantlius deltoides, Silene), Geranium [sylvaticum, 

 pyrenaicum, molle, pusillum), Erodium, Sedum, Semperviuum, Saxifragacese, 

 Rutacese (JRuta graveolens), Epilobium, PMlotheca australis, and Asarum 

 europseum ; and then those with a single row: — Lilium, Eremurus 

 spectabilis, MetJiomia superba, Trientalis europsea, Cobsea penduliflora, 

 0. scandens, Sabattia angularis, Valeriana officinalis, Linum, Boronia 

 pinnata, Puliurus aculeatus, Umbellifer^, Parnassia palustris, Teesdalia 

 nudicaulis, Faramea, Polygonum, Fagopyrum, Geratophyllum demersum, 

 and Eschscholtzia. 



The few cases in which actinomorphic flowers show contrivances for 

 "over-pollination" by iusects are also described, viz. : — Nigella, Passi- 

 Jlora, and Veratrum album ; and for lateral pollination : — Jasione montana, 

 Picris hieracioides, Leontodon auiumnalis, and Solanum rostratum. 



Of zygomorphic flowers those only are referred to which display 

 spontaneous motions and which are adapted for under-pollination : — 

 Delphinium, Aconitum, Beseda, Tropaeolum, Dictamnus, Polemonium, 

 ^scidus. 



These spontaneous movements are a very constant character of 

 families, and, being usually derived from the earliest periods, do not 

 disappear with the most complete changes in the parts of the flower. 



Irritability of Mimosa.* — Mr. D. D. Cunningham records the 

 result of a series of experiments on the phenomena of propagation of 

 movement in Mimosa pudica. He favoi;rs the view that it is due to 

 mechanical causes connected with the transference of water, together 

 with peculiarities in the structure of different masses of tissue, rather 

 than to the contractility of the protoplasm. The following are some 

 of the results on which this conclusion is founded. 



The intensity in the propagation of the movement is proportional 

 to the ease with which variations in the tensions of the tissues spread 

 themselves. The direction in which the movement advances is, in many 

 cases, that in which variations in the tensions of the tissues can be 

 determined ; while they cannot be explained as a result of protoplasmic 

 conduction. The order of succession of the excitations in cases of 

 advancing irritation is often inexplicable on the theory of a continuous 

 conduction of protoplasmic irritation, while it can easily be explained 

 as the result of variations of pressure in masses of tissue differing in 

 their anatomical structure. 



* Scient. Mem. by medical officers of the army of India, iii. (1888) pp. 83-138. 



