86 



KNOWLEDGE & SCIENTIFIC NEWS. 



[May, 1904. 



removed. I at first used 

 night exposures ; but this 



r.ia,:;T.eb!u:ii 

 was very 



laborious work. 

 I now use an incandescent lamp fed by methylated 

 spirits, but for those who are fortunate enough to 

 have electricity an arc lamp is best of all. When once 

 the right e.xposure is found all further difficulty in this 

 direction is removed. No doubt the ideal method would 

 be to ha\e a clockwork apparatus for turning the machine 

 which at the same time turned on the light and exposed 

 the plate, as Professor Pfefter has. 



The Sensitive Pla.r\t. — Mimosa seusitiva. 



This plant closes its leaves when touched, and also 

 naturally shuts them up at night. The leaf is divided 

 into two piniur, each divisi'^n bearing numerous leaf- 

 lets. The best way to make them work is to light a 

 match and put it under the end pair of leaflets at the 

 tip of one of the pinna of the leaf. The first pair of 

 leaflets then shut, then the second, and so on till the 



Climbing Plant {Mucuna nivca"\. 



Fig 29. 



Fig. 20. 



Fig. 28. 



Figs. 26 and 27.-Pliotographs. Show the tip of the stem turning round the support. 

 Fig. 2S.-Photograph. Shows the same tip appearing on the other side of the support. 

 Shows the tip applied closely to the support. 



Fig. 20. — Photograph. 



whole pinna is closed ; the same stimulus then closes the 

 two leaflets next the stalk of the neighbouring /jwm,, and 

 the leaflets close one after the other till the tip of the 

 leaf is reached. Every leaf on the same branch follows 

 suit, .\fter some time the leaf-stalk falls, another leaf 

 closes m the same way, until the effect of the stimulus is 

 at an end. These photographs are taken as quickly as 

 possible consistent with giving the right exposure, and 

 require a whole plate. 



A second plate shows the leaves reopening, taken at 

 intervals of about five minutes: the exposures were con- 

 tinued until the leaves shut into the sleep position for 

 the night. 



The more common species, .1/. pudica, serve equally 

 well lor experiment. 



The Weather ¥^\3.r\i.—Ahnts precahriiis. 

 There has been much discussion about this plant lately 

 as to whether it really predicts the weather to be expected 

 in the future. I have a series of photographs extending 



over one complete day, whici. ......v. the regular day and 



night movements of the plant. The plant was kept in a 

 glass case sheltered from wind and sun at a temperature 

 not below 73° F. = 22-5° C. The plant was placed with 

 the rachis (midrib) of its youngest leaf facing north. The 

 photograph was begun at 11.30 a.m. on Thursday, March 

 31, 1904, and continued until 10.30 p.m. It takes up the 

 sleep position at 4.30 p.m. Then the photograph was 

 begun again at 5 a.m. on .\pril i, while the leaves v.-ere 

 still shut. As the sun rises the leaflets gradually open, 

 and each leaf raises itself so quickly that one can watch 

 the movements easily. 



The kinematograph seems to afford a means of defi- 

 nitely settling this question. The photographs give an 

 unbiassed record of the movements of the plant and the 

 weather reports, barometrical and thermometrical read- 

 ings, records of earthquakes, &c., can be provided by the 

 various meteorological stations, so that if a re-investiga- 

 tion is ever considered necessary after Professor Oliver's* 

 exhaustive report on the subject the data 

 could in this way be obtained. 



Climbing Plants. — This is a very fas- 

 cinating subject for the Kammatograph. 

 ( )ne has to focus the support on which 

 the plant is climbing and to keep 

 the tip of the climbing stem in the held. 

 .\s the plant grows in length the Kam- 

 matograph has to be raised. In showing 

 the photograph with the lantern a jerk 

 will be noticed every time this is done, 

 so if it can be arranged to alter the 

 stand every morning one can see how 

 much the plant has twined each day. 

 Anyone who takes the trouble to photo- 

 graph a climbing plant will be surprised 

 at the very curious movements of the tip. 

 The way in which it circumnutates, turn- 

 ing to every point of the compass, then 

 gives a twist when it comes into contact 

 with its support, is very fascinating. 



The real difficulty with the climbing 

 plant is that it grows and climbs just 

 as much at night as it does in the day, 

 so that if it is not photographed at night 

 there is an interruption when projecting 

 it with the lantern corresponding to the 

 beginning of each new day. I am afraid 

 a perfect photograph of a climbing stem 

 will not be attained without clockwork 

 apparatus, as the trouble involved of sitting 

 up all night for at least a week would be too much to 

 expect, even of the most ardent photographer. 



The plant illustrated is a Calcutta stem-climber, 

 Muciina invca. It was photographed for a week from 

 6.30 a.m. to 11.30 p.m. 



I hope in these few pages that I may have succeeded 

 in interesting some of the readers of " Knowledge " in 

 the work of making animated pictures of plants, and 

 shall be only too glad if I can be of any use to anyone 

 who wishes to try these experiments. The illustrations 

 of such a subject are naturally disappointing, as they 

 cannot appear animated, but if anyone will take the 

 trouble to cut out the ten figures of the opening bud of 

 Sparmannia africana (Figs, i-io) and paste each on a card 

 or luggage label, and fasten them together closely at the 

 'ower end, by letting each figure pass before the eye they 

 appear animated and will give some rough idea of 



will 



what the plate will show when projected with a lantern. 

 • Kew Bulletin, Jan , 1890. 



