342 



TEE GARDENER'S MONTHLY 



[November, 



the rarest occurrence. And so gentle reader, 

 when you read of something attributed to some 

 favorite Avhom you believe in generally, but 

 which seems very absurd on this particular 

 occasion, be merciful to him and think that per- 

 adventure he did not do that foolish thing. 

 So may charity claim you for a client, when 

 your trial day comes round. 



Tropical Flora at the Poles. — As every in- 

 telligent person knows, the remains of tropical 

 plants and animals are found as far as explo- 

 rations have yet reached, and puzzle philos- 

 ophers to account for their appearance there. 

 Some have thought that through the long 

 course of ages the earth has gradually, and 

 perhaps may be still gradually, shifting its axis, 

 so that what is now the north may have been 

 under the line. The following from a recent 

 1 ecture by Mr. Blandet before the Geographical 

 Society of Paris, if true, might account for it 

 in another way, — for if the Sun was so large 

 every part of the earth would be warmed about 

 alike. We cannot of course decide between 

 these theories. The student must take his 

 choice. — 



" Oiir earth went, during its course in space, 

 through six periods : 1st. The chaotic period- 

 absence of all vegetable and animal life. 2nd. 

 Carboniferous period— the era of the immense 

 vegetable growth, which absorbed the carbonic 

 acid from the air, and the products buried 

 during successive convulsions of the earth, ex- 

 tended through various zones, as well under 

 the equator as near the poles. 3rd. The creta- 

 ceous period. 4th. The oecene period. 5th. 

 The miocene period— the primitive vegetation 

 leaves the poles, which cool down to below 

 the temperature necessary for life ; at the same 

 time nature, more choice in its products, gives 

 birth to animals more and more perfect. 6th. 

 The last or quaternary period, is that in which 

 we now live. 



"The continuous condensation of the sun is 

 alone sufficient to explain how it has been able 

 to furnish the prodigious quantity of heat which 

 it has radiated into space. The calculations 

 have been made: if it condense only enough 

 to diminish its apparent diameter one second 

 of an arc, it generates an amount of heat 

 equivalent to that which it emits in 18,000 

 years. 



"In the beginning of our earth's existence, 

 it rolled through a space of fire, the sun's 

 heated gases were extending beyond her orbit. 



The sun had then, as seen from the earth, a 

 diameter of 180°; this slowly became reduced 

 to 47°, next to 22°, next to 8°, and finally to 

 2° apparent diameter. 



" Then the quaternary period began ; the 

 poles commenced to cool, and only the tropics 

 received heat enough to sustain the luxurious 

 vegetation of the former periods. 



"The miocene period, or the time when the 

 tropical flora prevailed on the tops of the Pyr- 

 enees and Alps, and at the poles, when the sun 

 was 3°, or 180 minutes, or 10,000 seconds larger, 

 we go back 194,000,000 years before 244,000,000 

 years. Paris had, even later still, a tropical 

 temperature, and the eocene period existed 

 250,000,000 years before that time, or about 

 500,000,000 years previous to the present day. 



"But the carbonaceous era consists of 777,- 

 000,000 years more, making together about 

 1,-500,000,000 years. 



"The earth separated from the contracting 

 planetarj' nebula some 4,300,000,000 years be- 

 fore, making, as a total for the time of its in- 

 dependent existence, about 6,000,000,000 years. 



Vitality of Seed. — When a new form of 

 plant appears, the Botanist refers to all that 

 has been known about it before. We should 

 like to see this sort of knowledge attended to 

 in other branches. Mr. W. H. Seaman of Wash- 

 ington, has been doing this good work for ua 

 in relation to the question of vitality of seeds. 

 In Field and Forest, he has given references to 

 all he can find on the subject. There seems 

 to be little evidence worth considering that 

 seeds will live for ages in the ground. 



Course of the Sap. — Prof. Karl Koch says 

 in Gardeners' Chronicle : "Among practical gar- 

 deners and pomologigts not only does this error 

 respecting a. rising crude sap or raw food pre- 

 vail, but many of the current notions as to the 

 real nutritive substances are equally at fault; 

 more particularly that with regard to the direc- 

 tion of assimilated sap, which goes wherever it 

 is needed — that is to say, where it can nourish, 

 as a rule and for the greater part upwards, and 

 in a less degree downwards. In the first place, 

 nobody appears to have attempted to answer 

 the question. When do the leaves become active 

 or begin to assimilate the nutritive substances, 

 the carbon-hydrates? Nor, so for as I know, has 

 it been taken up from a scientific standpoint. 

 As the leaves are already green when they un- 

 fold, it has been tacutly admitted that assimi- 

 lation commences then. But such is by no 



