32 COLLECTING DIATOMS. 



" Let us step into a boat and examine that ship's bottom and 

 sides, which look so brown with a growth of conferva and barnacles. 

 Here the spoon becomes of use. Scrape very gently where the 

 deposit is the darkest in color, and let us see what we have got 

 Achnanthes longipes and brevipes in abundance. These are common 

 enough elsewhere in the timber ponds, so we will only secure the 

 little thing in zigzag filaments, for this is probably Diatoma hyaltnum, 

 or, perhaps, the rare Hyalosira delicatula. 



"Is it not singular that such delicate filaments, hanging together by 

 the angles of the frustules, should be able to withstand the rushing of 

 the vessel through the water during the long voyage she has just com- 

 pleted ? 



" The ballast-heap must not be passed without examining. Here are 

 stones densely covered with marine Algae and Corallines, which we will 

 scrape off and store away for after-examination. Biddulphia pulche/la, 

 Aniphitetras, Grammatophara serpentina, or possibly some of the beautiful 

 foreign species of Aulacodiscus, may reward our trouble, for this ballast 

 is brought from all parts of the world. The only matter of regret is 

 the difficulty in ascertaining the exact localities. 



" Let us now take some of the Zostera which is being landed on 

 the quay in large bales ; it is extensively imported from the Baltic as 

 Ulva marina, for stuffing chairs and mattresses. Cocconeis scutettum and 

 diaphana, with Epilhemia and a medley of other forms, are generally 

 found parasitic on the Zostera, and may be easily separated by macera- 

 tion in weak acid. 



" But what are those brown bundles landing from the steamer? 

 These are " Dutch rushes," for coopers' purposes and chair-bottoms, and 

 are well worth examining, for, growing as they do in brackish water 

 in Holland, the sheath at the base is often completely coated with 

 diatoms, Coscinodiscus subtilis, for instance, with other good things, such 

 as Enpodiscus argus and Triceratium favus. 



' Nor must we pass these cargoes of bones discharging into lighters. 

 See, some of the larger bones have evidently been lying in the water 

 some time, for they are covered with a green incrustation. Let us 

 scrape away the incrustation, for we may find among it the fine Synedra 

 crystallina or undulata, together with valves of Coscinodiscus and Eupodiscus. 

 Many good gatherings have been procured from this source, especially 

 from cargoes coming from Constantinople, Smyrna, and the Black Sea. 



"Ask this sailor if he has any foreign shells still in the rough state; 

 if he has any for sale, they are certainly worth securing for the small 



