HARDWICKE'S SCIENCE-GOSSIP. 



12 r 



GRAPHIC MICROSCOPY. 



By E. T. DRAPER 



No. XVIII. — Seeds of Love-lies-bleeding {Amaranthus caudatus). 



UR plate exhibits 

 simply the external 

 character and 

 appearance of an 

 elegant seed, as seen 

 with a moderate 

 power under the 

 microscope. From 

 this aspect the 

 subject is intro- 

 duced, to invite 

 attention to an 

 attractive class of 

 e a s ily-p rocured 

 objects, showing 

 elegance of form 

 and colour. 



The microscopist, 

 however, contem- 

 plates a seed with 

 deeper significance, its hidden mystery, its absolute 

 totality, an independent whole, involving an embryo 

 lying dormant (often for years), but ready, under 

 favourable surroundings, to start a new plant true to 

 its species. At such a point it may be interesting to 

 devote a few preliminary lines in an attempt to de- 

 scribe what may be seen of this compacted quiescence 

 when set in action by the force of germination, and 

 revealed by the instrument. 



In a dry, intact seed, the embryo of the future 

 plant is hidden beyond the power of observation, 

 but when subjected to external influences alterations 

 commence. At this stage, examination leads the 

 imagination to what may have been the primary 

 condition ; a germ, enclosed in a simple and minute 

 cylindrical body of dense organisation hardly pre- 

 senting a trace of complicated or differentiated 

 structures, and only when influenced by moisture 

 and moderate heat the mysterious principle "ger- 

 mination " sets in ; changes appear by the gradual ab- 

 sorption and elimination of the surrounding and pro- 

 tecting provision ; the embryo then breaks through the 

 No. 246.— June 1885. 



integuments and acquires a distinct vascular, tubular, 

 and cellular organisation ; this process, or develop 

 ment, may be observed. A grain of corn, although 

 partaking more of the character of a fruit than a seed, 

 is peculiarly adapted for experiment ; by soaking in 

 water for a few hours germination is quickly pro- 

 moted ; to see the acme of interest, it must not be 

 carried too far, in fact, just started ; thin transparent 

 sections cut from the centre of the grain in the direc- 

 tion of the axis, and placed under a thin glass cover 

 in a drop of glycerine jelly or chloride of calcium, 

 will exhibit developments which may be assumed to 

 be analogous to the germination of other seeds ; a 

 minute sheath, or sac, formed by the single cotyledon, 

 which represents the undeveloped leaves, will be seen, 

 enclosing the plumule, the rudiment of the ascending 

 growth ; outside the sheath, the radicle, the nascent 

 descending axis. These organs, still confined within 

 the seed, or at least, only just breaking through the 

 pericarp or outer skin, are sustained by the exhaustion 

 of the albumen of which the greater part of the seed 

 consists, stored in cells — reservoirs of nutriment, 

 starches, oils, and other matters in varied combina- 

 tions. Cuttings from grains, soaked in water, taken 

 at successive periods, exhibit phases or progresses of 

 development. But, from an embryological point of 

 view, microscopical interest is lost after the initial 

 process is past ; the albumen cells then become 

 exhausted and effete, and the minute stem and root 

 push forth and assume the character of a plant, 

 entirely dependent on external resources. A trans- 

 verse section cut through the point of a germinating 

 grain shows the cotyledon like a pale oval border, 

 surrounding the minute and compacted convoluted 

 tissues, which afterwards become the leaves of the 

 plumule. 



The gay and persistent blossoms of the somewhat 

 weedy shrub-like Amaranthus caudatus (love-lies- 

 bleeding) are prominently attractive in old-fashioned 

 gardens ; the fruit is a utricle, a seed vessel with a 

 loose rind, or pericarp ; rubbed off, or winnowed, it 

 reveals the object, as seen in the illustration ; i.i 



G 



