October, 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



249 



upon (see Fii,^. 4c, which represents a group of zoo- 

 spores setthng on a strand of cotton-wool). 



If, now, the basin of sea water, with a supply of 

 Cladophora, is placed aside for an hour or twO', a 

 green scum appears on it. This is due to myriads of 

 zoospores, which have come tO' the top, because they 

 love the light. Pour some of the scum intO' a potted- 

 meat pot, and place It in the sun. The green all 

 assembles on the sunny side. Cover it over with a 



Fig. 4. 



paper in which you have cut a stencil of your initials. 

 In a few minutes, the tiny green creatures do you the 

 honour of inscribing those illustrious letters on the 

 watery tablet beneath. Put a drop of the scum under 

 the microscope, and illuminate it from below. The 

 zoospores are seen swimming aimlessly about in their 

 thousands. But shut off the light below, and throw 

 a strong light from the side. Instantly the whole 

 crowd of zoospores turn with their pointed anterior 

 ends to the light, and there ensues a stampede in that 

 direction. Now examine the edge of the drop, tO' see 

 what is going on at that goal to which this crowd of 

 beings is hastening. P\. struggle to the death is going 

 on. Hundreds of spores are fighting there for room — 

 hundreds more fling themselves on the struggling mass, 

 and numbers perish. .A.nd what we see in this tiny 

 drop may be seen on many a fine day in summer in the 

 pools on the shore, where the green scum collects, 

 always densest on the edge that gets the sun. 



The advantage of this love of light is obvious. If 

 any misguided spore hated the light, it would settle 

 in the darkest corner of the pool, and, on beginning to 

 grow, would perish miserably from lack of that food- 

 stuff — starch, sugar — which it is unable to work up 

 without sunshine. 



It is an exceedingly interesting fact that the brown 



Eclocarpus described above produces swimming bodies 

 which appear to be identical with those of Cladophora 

 C^'g- .S)- B"' while some of these can grow at once 

 into new plants, others unite in pairs, and, therefore, 

 act as sexual elements. Here, therefore, we see the 

 very beginning of that sexual process which is so 

 marked a feature in the brown seaweeds and the red. 



In Ectocarpus there is no apparent difference between 

 the male and the female cells ; but inasmuch as it is a 

 distinct advantage for a cell from which a new genera- 

 tion will spring to- be possessed of a store of fooa 

 ^naterial, we find in the higher brown seaweeds the 

 large, inactive female, or ^^^ cell, which has been 

 already described, while the male cell remains minufe 

 and active. In the red seaweeds the female organ puts 

 out a special hair-like cell which projects into the water, 

 and mterce[)ts the male cell. Tliis last is, strange to 

 say, destitute of cilia ; it is swept about in the water 

 until by good luck, it reaches its goal. 



.Such are some of the delights that await the field 

 botanist on ths shore. The seaweeds appeal to his 

 artistic, poetic, scientific, and speculative faculties. We 

 see in them life in some of its lowliest aspects, feeling 

 its way up to> greater utility, greater beauty (which is 

 more perfect the more it is associated with utility), and 

 to habits and customs that make for greater success 



Fig. 5. 



in life. Lilc. we repeat, at its lowest. They have no 

 eyes, yet they see ; no nerves, yet they feel ; no muscles, 

 yet they move ; and they exhibit in simple fashion that 

 passion which, in its highest exemplifications, is 

 described as "tender." In the protoplasm of which 

 their bodies are built reside all the possibilities of 

 life. Our own bodies are built up of and by proto- 

 plasm ; and we ourselves can do very little more than 

 the seaweeds that dwell on our shore. 



Answers to Correspondents, 



.V;s. ]oUy. — Reflected Sunlight. — The light of the sun. 

 which is estimated to be some 3^ times as bright as that of 

 an electric arc light, is so intense that when reflected off 

 the surface of the moon it causes the latter to "shine." 

 Various surfaces reflect light in dift'erent degrees. Thus a 

 window pane, even many miles away, will reflect the sun in 

 dazzling brilliancy, and the sun shining on snow causes so great 

 a glare as to necessitate the wearing of dark goggles. 



li. Cliristoplur. — D.\rk St.\ks. — You suggest that such bodies 

 " belong, of course, to our solar system." We believe that 

 no such assertion has been made by astronomers. The dark 

 stars referred to are supposed to exist in space, but far beyond 

 the distance at which they would reflect the sun's light. In 

 our next issue we are hoping to insert an article by Mr. Gore, 

 which refers to this subject. 



